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diff --git a/extra/jemalloc/doc/jemalloc.html b/extra/jemalloc/doc/jemalloc.html new file mode 100644 index 00000000000..3e0fe26d1bd --- /dev/null +++ b/extra/jemalloc/doc/jemalloc.html @@ -0,0 +1,1417 @@ +<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>JEMALLOC</title><meta name="generator" content="DocBook XSL Stylesheets V1.76.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" title="JEMALLOC"><a name="id286949159"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>jemalloc — general purpose memory allocation functions</p></div><div class="refsect1" title="LIBRARY"><a name="library"></a><h2>LIBRARY</h2><p>This manual describes jemalloc 3.3.1-0-g9ef9d9e8c271cdf14f664b871a8f98c827714784. More information + can be found at the <a class="ulink" href="http://www.canonware.com/jemalloc/" target="_top">jemalloc website</a>.</p></div><div class="refsynopsisdiv" title="SYNOPSIS"><h2>SYNOPSIS</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <<code class="filename">stdlib.h</code>> +#include <<code class="filename">jemalloc/jemalloc.h</code>></pre><div class="refsect2" title="Standard API"><a name="id286901505"></a><h3>Standard API</h3><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void *<b class="fsfunc">malloc</b>(</code></td><td>size_t <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void *<b class="fsfunc">calloc</b>(</code></td><td>size_t <var class="pdparam">number</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">posix_memalign</b>(</code></td><td>void **<var class="pdparam">ptr</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">alignment</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void *<b class="fsfunc">aligned_alloc</b>(</code></td><td>size_t <var class="pdparam">alignment</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void *<b class="fsfunc">realloc</b>(</code></td><td>void *<var class="pdparam">ptr</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">free</b>(</code></td><td>void *<var class="pdparam">ptr</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><div class="refsect2" title="Non-standard API"><a name="id286900549"></a><h3>Non-standard API</h3><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">size_t <b class="fsfunc">malloc_usable_size</b>(</code></td><td>const void *<var class="pdparam">ptr</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">malloc_stats_print</b>(</code></td><td>void <var class="pdparam">(*write_cb)</var> + <code>(</code>void *, const char *<code>)</code> + , </td></tr><tr><td> </td><td>void *<var class="pdparam">cbopaque</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">opts</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">mallctl</b>(</code></td><td>const char *<var class="pdparam">name</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">oldp</var>, </td></tr><tr><td> </td><td>size_t *<var class="pdparam">oldlenp</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">newp</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">newlen</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">mallctlnametomib</b>(</code></td><td>const char *<var class="pdparam">name</var>, </td></tr><tr><td> </td><td>size_t *<var class="pdparam">mibp</var>, </td></tr><tr><td> </td><td>size_t *<var class="pdparam">miblenp</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">mallctlbymib</b>(</code></td><td>const size_t *<var class="pdparam">mib</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">miblen</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">oldp</var>, </td></tr><tr><td> </td><td>size_t *<var class="pdparam">oldlenp</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">newp</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">newlen</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">(*malloc_message)</b>(</code></td><td>void *<var class="pdparam">cbopaque</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">s</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><p><span class="type">const char *</span><code class="varname">malloc_conf</code>;</p></div><div class="refsect2" title="Experimental API"><a name="id286900756"></a><h3>Experimental API</h3><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">allocm</b>(</code></td><td>void **<var class="pdparam">ptr</var>, </td></tr><tr><td> </td><td>size_t *<var class="pdparam">rsize</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">rallocm</b>(</code></td><td>void **<var class="pdparam">ptr</var>, </td></tr><tr><td> </td><td>size_t *<var class="pdparam">rsize</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">extra</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">sallocm</b>(</code></td><td>const void *<var class="pdparam">ptr</var>, </td></tr><tr><td> </td><td>size_t *<var class="pdparam">rsize</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">dallocm</b>(</code></td><td>void *<var class="pdparam">ptr</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">nallocm</b>(</code></td><td>size_t *<var class="pdparam">rsize</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div></div><div class="refsect1" title="DESCRIPTION"><a name="description"></a><h2>DESCRIPTION</h2><div class="refsect2" title="Standard API"><a name="id286949297"></a><h3>Standard API</h3><p>The <code class="function">malloc</code>(<em class="parameter"><code></code></em>) function allocates + <em class="parameter"><code>size</code></em> bytes of uninitialized memory. The allocated + space is suitably aligned (after possible pointer coercion) for storage + of any type of object.</p><p>The <code class="function">calloc</code>(<em class="parameter"><code></code></em>) function allocates + space for <em class="parameter"><code>number</code></em> objects, each + <em class="parameter"><code>size</code></em> bytes in length. The result is identical to + calling <code class="function">malloc</code>(<em class="parameter"><code></code></em>) with an argument of + <em class="parameter"><code>number</code></em> * <em class="parameter"><code>size</code></em>, with the + exception that the allocated memory is explicitly initialized to zero + bytes.</p><p>The <code class="function">posix_memalign</code>(<em class="parameter"><code></code></em>) function + allocates <em class="parameter"><code>size</code></em> bytes of memory such that the + allocation's base address is an even multiple of + <em class="parameter"><code>alignment</code></em>, and returns the allocation in the value + pointed to by <em class="parameter"><code>ptr</code></em>. The requested + <em class="parameter"><code>alignment</code></em> must be a power of 2 at least as large + as <code class="code">sizeof(<span class="type">void *</span>)</code>.</p><p>The <code class="function">aligned_alloc</code>(<em class="parameter"><code></code></em>) function + allocates <em class="parameter"><code>size</code></em> bytes of memory such that the + allocation's base address is an even multiple of + <em class="parameter"><code>alignment</code></em>. The requested + <em class="parameter"><code>alignment</code></em> must be a power of 2. Behavior is + undefined if <em class="parameter"><code>size</code></em> is not an integral multiple of + <em class="parameter"><code>alignment</code></em>.</p><p>The <code class="function">realloc</code>(<em class="parameter"><code></code></em>) function changes the + size of the previously allocated memory referenced by + <em class="parameter"><code>ptr</code></em> to <em class="parameter"><code>size</code></em> bytes. The + contents of the memory are unchanged up to the lesser of the new and old + sizes. If the new size is larger, the contents of the newly allocated + portion of the memory are undefined. Upon success, the memory referenced + by <em class="parameter"><code>ptr</code></em> is freed and a pointer to the newly + allocated memory is returned. Note that + <code class="function">realloc</code>(<em class="parameter"><code></code></em>) may move the memory allocation, + resulting in a different return value than <em class="parameter"><code>ptr</code></em>. + If <em class="parameter"><code>ptr</code></em> is <code class="constant">NULL</code>, the + <code class="function">realloc</code>(<em class="parameter"><code></code></em>) function behaves identically to + <code class="function">malloc</code>(<em class="parameter"><code></code></em>) for the specified size.</p><p>The <code class="function">free</code>(<em class="parameter"><code></code></em>) function causes the + allocated memory referenced by <em class="parameter"><code>ptr</code></em> to be made + available for future allocations. If <em class="parameter"><code>ptr</code></em> is + <code class="constant">NULL</code>, no action occurs.</p></div><div class="refsect2" title="Non-standard API"><a name="id286949561"></a><h3>Non-standard API</h3><p>The <code class="function">malloc_usable_size</code>(<em class="parameter"><code></code></em>) function + returns the usable size of the allocation pointed to by + <em class="parameter"><code>ptr</code></em>. The return value may be larger than the size + that was requested during allocation. The + <code class="function">malloc_usable_size</code>(<em class="parameter"><code></code></em>) function is not a + mechanism for in-place <code class="function">realloc</code>(<em class="parameter"><code></code></em>); rather + it is provided solely as a tool for introspection purposes. Any + discrepancy between the requested allocation size and the size reported + by <code class="function">malloc_usable_size</code>(<em class="parameter"><code></code></em>) should not be + depended on, since such behavior is entirely implementation-dependent. + </p><p>The <code class="function">malloc_stats_print</code>(<em class="parameter"><code></code></em>) function + writes human-readable summary statistics via the + <em class="parameter"><code>write_cb</code></em> callback function pointer and + <em class="parameter"><code>cbopaque</code></em> data passed to + <em class="parameter"><code>write_cb</code></em>, or + <code class="function">malloc_message</code>(<em class="parameter"><code></code></em>) if + <em class="parameter"><code>write_cb</code></em> is <code class="constant">NULL</code>. This + function can be called repeatedly. General information that never + changes during execution can be omitted by specifying "g" as a character + within the <em class="parameter"><code>opts</code></em> string. Note that + <code class="function">malloc_message</code>(<em class="parameter"><code></code></em>) uses the + <code class="function">mallctl*</code>(<em class="parameter"><code></code></em>) functions internally, so + inconsistent statistics can be reported if multiple threads use these + functions simultaneously. If <code class="option">--enable-stats</code> is + specified during configuration, “m” and “a” can + be specified to omit merged arena and per arena statistics, respectively; + “b” and “l” can be specified to omit per size + class statistics for bins and large objects, respectively. Unrecognized + characters are silently ignored. Note that thread caching may prevent + some statistics from being completely up to date, since extra locking + would be required to merge counters that track thread cache operations. + </p><p>The <code class="function">mallctl</code>(<em class="parameter"><code></code></em>) function provides a + general interface for introspecting the memory allocator, as well as + setting modifiable parameters and triggering actions. The + period-separated <em class="parameter"><code>name</code></em> argument specifies a + location in a tree-structured namespace; see the <a class="xref" href="#mallctl_namespace" title="MALLCTL NAMESPACE">MALLCTL NAMESPACE</a> section for + documentation on the tree contents. To read a value, pass a pointer via + <em class="parameter"><code>oldp</code></em> to adequate space to contain the value, and a + pointer to its length via <em class="parameter"><code>oldlenp</code></em>; otherwise pass + <code class="constant">NULL</code> and <code class="constant">NULL</code>. Similarly, to + write a value, pass a pointer to the value via + <em class="parameter"><code>newp</code></em>, and its length via + <em class="parameter"><code>newlen</code></em>; otherwise pass <code class="constant">NULL</code> + and <code class="constant">0</code>.</p><p>The <code class="function">mallctlnametomib</code>(<em class="parameter"><code></code></em>) function + provides a way to avoid repeated name lookups for applications that + repeatedly query the same portion of the namespace, by translating a name + to a “Management Information Base” (MIB) that can be passed + repeatedly to <code class="function">mallctlbymib</code>(<em class="parameter"><code></code></em>). Upon + successful return from <code class="function">mallctlnametomib</code>(<em class="parameter"><code></code></em>), + <em class="parameter"><code>mibp</code></em> contains an array of + <em class="parameter"><code>*miblenp</code></em> integers, where + <em class="parameter"><code>*miblenp</code></em> is the lesser of the number of components + in <em class="parameter"><code>name</code></em> and the input value of + <em class="parameter"><code>*miblenp</code></em>. Thus it is possible to pass a + <em class="parameter"><code>*miblenp</code></em> that is smaller than the number of + period-separated name components, which results in a partial MIB that can + be used as the basis for constructing a complete MIB. For name + components that are integers (e.g. the 2 in + <a class="link" href="#arenas.bin.i.size"> + "<code class="mallctl">arenas.bin.2.size</code>" + </a>), + the corresponding MIB component will always be that integer. Therefore, + it is legitimate to construct code like the following: </p><pre class="programlisting"> +unsigned nbins, i; + +int mib[4]; +size_t len, miblen; + +len = sizeof(nbins); +mallctl("arenas.nbins", &nbins, &len, NULL, 0); + +miblen = 4; +mallnametomib("arenas.bin.0.size", mib, &miblen); +for (i = 0; i < nbins; i++) { + size_t bin_size; + + mib[2] = i; + len = sizeof(bin_size); + mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0); + /* Do something with bin_size... */ +}</pre></div><div class="refsect2" title="Experimental API"><a name="id286949870"></a><h3>Experimental API</h3><p>The experimental API is subject to change or removal without regard + for backward compatibility. If <code class="option">--disable-experimental</code> + is specified during configuration, the experimental API is + omitted.</p><p>The <code class="function">allocm</code>(<em class="parameter"><code></code></em>), + <code class="function">rallocm</code>(<em class="parameter"><code></code></em>), + <code class="function">sallocm</code>(<em class="parameter"><code></code></em>), + <code class="function">dallocm</code>(<em class="parameter"><code></code></em>), and + <code class="function">nallocm</code>(<em class="parameter"><code></code></em>) functions all have a + <em class="parameter"><code>flags</code></em> argument that can be used to specify + options. The functions only check the options that are contextually + relevant. Use bitwise or (<code class="code">|</code>) operations to + specify one or more of the following: + </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">ALLOCM_LG_ALIGN(<em class="parameter"><code>la</code></em>) + </code></span></dt><dd><p>Align the memory allocation to start at an address + that is a multiple of <code class="code">(1 << + <em class="parameter"><code>la</code></em>)</code>. This macro does not validate + that <em class="parameter"><code>la</code></em> is within the valid + range.</p></dd><dt><span class="term"><code class="constant">ALLOCM_ALIGN(<em class="parameter"><code>a</code></em>) + </code></span></dt><dd><p>Align the memory allocation to start at an address + that is a multiple of <em class="parameter"><code>a</code></em>, where + <em class="parameter"><code>a</code></em> is a power of two. This macro does not + validate that <em class="parameter"><code>a</code></em> is a power of 2. + </p></dd><dt><span class="term"><code class="constant">ALLOCM_ZERO</code></span></dt><dd><p>Initialize newly allocated memory to contain zero + bytes. In the growing reallocation case, the real size prior to + reallocation defines the boundary between untouched bytes and those + that are initialized to contain zero bytes. If this option is + absent, newly allocated memory is uninitialized.</p></dd><dt><span class="term"><code class="constant">ALLOCM_NO_MOVE</code></span></dt><dd><p>For reallocation, fail rather than moving the + object. This constraint can apply to both growth and + shrinkage.</p></dd><dt><span class="term"><code class="constant">ALLOCM_ARENA(<em class="parameter"><code>a</code></em>) + </code></span></dt><dd><p>Use the arena specified by the index + <em class="parameter"><code>a</code></em>. This macro does not validate that + <em class="parameter"><code>a</code></em> specifies an arena in the valid + range.</p></dd></dl></div><p> + </p><p>The <code class="function">allocm</code>(<em class="parameter"><code></code></em>) function allocates at + least <em class="parameter"><code>size</code></em> bytes of memory, sets + <em class="parameter"><code>*ptr</code></em> to the base address of the allocation, and + sets <em class="parameter"><code>*rsize</code></em> to the real size of the allocation if + <em class="parameter"><code>rsize</code></em> is not <code class="constant">NULL</code>. Behavior + is undefined if <em class="parameter"><code>size</code></em> is + <code class="constant">0</code>.</p><p>The <code class="function">rallocm</code>(<em class="parameter"><code></code></em>) function resizes the + allocation at <em class="parameter"><code>*ptr</code></em> to be at least + <em class="parameter"><code>size</code></em> bytes, sets <em class="parameter"><code>*ptr</code></em> to + the base address of the allocation if it moved, and sets + <em class="parameter"><code>*rsize</code></em> to the real size of the allocation if + <em class="parameter"><code>rsize</code></em> is not <code class="constant">NULL</code>. If + <em class="parameter"><code>extra</code></em> is non-zero, an attempt is made to resize + the allocation to be at least <code class="code"><em class="parameter"><code>size</code></em> + + <em class="parameter"><code>extra</code></em>)</code> bytes, though inability to allocate + the extra byte(s) will not by itself result in failure. Behavior is + undefined if <em class="parameter"><code>size</code></em> is <code class="constant">0</code>, or if + <code class="code">(<em class="parameter"><code>size</code></em> + + <em class="parameter"><code>extra</code></em> > + <code class="constant">SIZE_T_MAX</code>)</code>.</p><p>The <code class="function">sallocm</code>(<em class="parameter"><code></code></em>) function sets + <em class="parameter"><code>*rsize</code></em> to the real size of the allocation.</p><p>The <code class="function">dallocm</code>(<em class="parameter"><code></code></em>) function causes the + memory referenced by <em class="parameter"><code>ptr</code></em> to be made available for + future allocations.</p><p>The <code class="function">nallocm</code>(<em class="parameter"><code></code></em>) function allocates no + memory, but it performs the same size computation as the + <code class="function">allocm</code>(<em class="parameter"><code></code></em>) function, and if + <em class="parameter"><code>rsize</code></em> is not <code class="constant">NULL</code> it sets + <em class="parameter"><code>*rsize</code></em> to the real size of the allocation that + would result from the equivalent <code class="function">allocm</code>(<em class="parameter"><code></code></em>) + function call. Behavior is undefined if + <em class="parameter"><code>size</code></em> is <code class="constant">0</code>.</p></div></div><div class="refsect1" title="TUNING"><a name="tuning"></a><h2>TUNING</h2><p>Once, when the first call is made to one of the memory allocation + routines, the allocator initializes its internals based in part on various + options that can be specified at compile- or run-time.</p><p>The string pointed to by the global variable + <code class="varname">malloc_conf</code>, the “name” of the file + referenced by the symbolic link named <code class="filename">/etc/malloc.conf</code>, and the value of the + environment variable <code class="envar">MALLOC_CONF</code>, will be interpreted, in + that order, from left to right as options.</p><p>An options string is a comma-separated list of option:value pairs. + There is one key corresponding to each <a class="link" href="#opt.abort"> + "<code class="mallctl">opt.*</code>" + </a> mallctl (see the <a class="xref" href="#mallctl_namespace" title="MALLCTL NAMESPACE">MALLCTL NAMESPACE</a> section for options + documentation). For example, <code class="literal">abort:true,narenas:1</code> sets + the <a class="link" href="#opt.abort"> + "<code class="mallctl">opt.abort</code>" + </a> and <a class="link" href="#opt.narenas"> + "<code class="mallctl">opt.narenas</code>" + </a> options. Some + options have boolean values (true/false), others have integer values (base + 8, 10, or 16, depending on prefix), and yet others have raw string + values.</p></div><div class="refsect1" title="IMPLEMENTATION NOTES"><a name="implementation_notes"></a><h2>IMPLEMENTATION NOTES</h2><p>Traditionally, allocators have used + <span class="citerefentry"><span class="refentrytitle">sbrk</span>(2)</span> to obtain memory, which is + suboptimal for several reasons, including race conditions, increased + fragmentation, and artificial limitations on maximum usable memory. If + <code class="option">--enable-dss</code> is specified during configuration, this + allocator uses both <span class="citerefentry"><span class="refentrytitle">mmap</span>(2)</span> and + <span class="citerefentry"><span class="refentrytitle">sbrk</span>(2)</span>, in that order of preference; + otherwise only <span class="citerefentry"><span class="refentrytitle">mmap</span>(2)</span> is used.</p><p>This allocator uses multiple arenas in order to reduce lock + contention for threaded programs on multi-processor systems. This works + well with regard to threading scalability, but incurs some costs. There is + a small fixed per-arena overhead, and additionally, arenas manage memory + completely independently of each other, which means a small fixed increase + in overall memory fragmentation. These overheads are not generally an + issue, given the number of arenas normally used. Note that using + substantially more arenas than the default is not likely to improve + performance, mainly due to reduced cache performance. However, it may make + sense to reduce the number of arenas if an application does not make much + use of the allocation functions.</p><p>In addition to multiple arenas, unless + <code class="option">--disable-tcache</code> is specified during configuration, this + allocator supports thread-specific caching for small and large objects, in + order to make it possible to completely avoid synchronization for most + allocation requests. Such caching allows very fast allocation in the + common case, but it increases memory usage and fragmentation, since a + bounded number of objects can remain allocated in each thread cache.</p><p>Memory is conceptually broken into equal-sized chunks, where the + chunk size is a power of two that is greater than the page size. Chunks + are always aligned to multiples of the chunk size. This alignment makes it + possible to find metadata for user objects very quickly.</p><p>User objects are broken into three categories according to size: + small, large, and huge. Small objects are smaller than one page. Large + objects are smaller than the chunk size. Huge objects are a multiple of + the chunk size. Small and large objects are managed by arenas; huge + objects are managed separately in a single data structure that is shared by + all threads. Huge objects are used by applications infrequently enough + that this single data structure is not a scalability issue.</p><p>Each chunk that is managed by an arena tracks its contents as runs of + contiguous pages (unused, backing a set of small objects, or backing one + large object). The combination of chunk alignment and chunk page maps + makes it possible to determine all metadata regarding small and large + allocations in constant time.</p><p>Small objects are managed in groups by page runs. Each run maintains + a frontier and free list to track which regions are in use. Allocation + requests that are no more than half the quantum (8 or 16, depending on + architecture) are rounded up to the nearest power of two that is at least + <code class="code">sizeof(<span class="type">double</span>)</code>. All other small + object size classes are multiples of the quantum, spaced such that internal + fragmentation is limited to approximately 25% for all but the smallest size + classes. Allocation requests that are larger than the maximum small size + class, but small enough to fit in an arena-managed chunk (see the <a class="link" href="#opt.lg_chunk"> + "<code class="mallctl">opt.lg_chunk</code>" + </a> option), are + rounded up to the nearest run size. Allocation requests that are too large + to fit in an arena-managed chunk are rounded up to the nearest multiple of + the chunk size.</p><p>Allocations are packed tightly together, which can be an issue for + multi-threaded applications. If you need to assure that allocations do not + suffer from cacheline sharing, round your allocation requests up to the + nearest multiple of the cacheline size, or specify cacheline alignment when + allocating.</p><p>Assuming 4 MiB chunks, 4 KiB pages, and a 16-byte quantum on a 64-bit + system, the size classes in each category are as shown in <a class="xref" href="#size_classes" title="Table 1. Size classes">Table 1</a>.</p><div class="table"><a name="size_classes"></a><p class="title"><b>Table 1. Size classes</b></p><div class="table-contents"><table summary="Size classes" border="1"><colgroup><col align="left" class="c1"><col align="right" class="c2"><col align="left" class="c3"></colgroup><thead><tr><th align="left">Category</th><th align="right">Spacing</th><th align="left">Size</th></tr></thead><tbody><tr><td rowspan="7" align="left">Small</td><td align="right">lg</td><td align="left">[8]</td></tr><tr><td align="right">16</td><td align="left">[16, 32, 48, ..., 128]</td></tr><tr><td align="right">32</td><td align="left">[160, 192, 224, 256]</td></tr><tr><td align="right">64</td><td align="left">[320, 384, 448, 512]</td></tr><tr><td align="right">128</td><td align="left">[640, 768, 896, 1024]</td></tr><tr><td align="right">256</td><td align="left">[1280, 1536, 1792, 2048]</td></tr><tr><td align="right">512</td><td align="left">[2560, 3072, 3584]</td></tr><tr><td align="left">Large</td><td align="right">4 KiB</td><td align="left">[4 KiB, 8 KiB, 12 KiB, ..., 4072 KiB]</td></tr><tr><td align="left">Huge</td><td align="right">4 MiB</td><td align="left">[4 MiB, 8 MiB, 12 MiB, ...]</td></tr></tbody></table></div></div><br class="table-break"></div><div class="refsect1" title="MALLCTL NAMESPACE"><a name="mallctl_namespace"></a><h2>MALLCTL NAMESPACE</h2><p>The following names are defined in the namespace accessible via the + <code class="function">mallctl*</code>(<em class="parameter"><code></code></em>) functions. Value types are + specified in parentheses, their readable/writable statuses are encoded as + <code class="literal">rw</code>, <code class="literal">r-</code>, <code class="literal">-w</code>, or + <code class="literal">--</code>, and required build configuration flags follow, if + any. A name element encoded as <code class="literal"><i></code> or + <code class="literal"><j></code> indicates an integer component, where the + integer varies from 0 to some upper value that must be determined via + introspection. In the case of + "<code class="mallctl">stats.arenas.<i>.*</code>" + , + <code class="literal"><i></code> equal to <a class="link" href="#arenas.narenas"> + "<code class="mallctl">arenas.narenas</code>" + </a> can be + used to access the summation of statistics from all arenas. Take special + note of the <a class="link" href="#epoch"> + "<code class="mallctl">epoch</code>" + </a> mallctl, + which controls refreshing of cached dynamic statistics.</p><div class="variablelist"><dl><dt><span class="term"> + + "<code class="mallctl">version</code>" + + (<span class="type">const char *</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Return the jemalloc version string.</p></dd><dt><a name="epoch"></a><span class="term"> + + "<code class="mallctl">epoch</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">rw</code> + </span></dt><dd><p>If a value is passed in, refresh the data from which + the <code class="function">mallctl*</code>(<em class="parameter"><code></code></em>) functions report values, + and increment the epoch. Return the current epoch. This is useful for + detecting whether another thread caused a refresh.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.debug</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-debug</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.dss</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-dss</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.fill</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-fill</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.lazy_lock</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-lazy-lock</code> was specified + during build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.mremap</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-mremap</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.munmap</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-munmap</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.prof</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-prof</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.prof_libgcc</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--disable-prof-libgcc</code> was not + specified during build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.prof_libunwind</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-prof-libunwind</code> was specified + during build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.stats</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-stats</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.tcache</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--disable-tcache</code> was not specified + during build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.tls</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--disable-tls</code> was not specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.utrace</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-utrace</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.valgrind</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-valgrind</code> was specified during + build configuration.</p></dd><dt><span class="term"> + + "<code class="mallctl">config.xmalloc</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p><code class="option">--enable-xmalloc</code> was specified during + build configuration.</p></dd><dt><a name="opt.abort"></a><span class="term"> + + "<code class="mallctl">opt.abort</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Abort-on-warning enabled/disabled. If true, most + warnings are fatal. The process will call + <span class="citerefentry"><span class="refentrytitle">abort</span>(3)</span> in these cases. This option is + disabled by default unless <code class="option">--enable-debug</code> is + specified during configuration, in which case it is enabled by default. + </p></dd><dt><a name="opt.lg_chunk"></a><span class="term"> + + "<code class="mallctl">opt.lg_chunk</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Virtual memory chunk size (log base 2). If a chunk + size outside the supported size range is specified, the size is + silently clipped to the minimum/maximum supported size. The default + chunk size is 4 MiB (2^22). + </p></dd><dt><a name="opt.dss"></a><span class="term"> + + "<code class="mallctl">opt.dss</code>" + + (<span class="type">const char *</span>) + <code class="literal">r-</code> + </span></dt><dd><p>dss (<span class="citerefentry"><span class="refentrytitle">sbrk</span>(2)</span>) allocation precedence as + related to <span class="citerefentry"><span class="refentrytitle">mmap</span>(2)</span> allocation. The following + settings are supported: “disabled”, “primary”, + and “secondary” (default).</p></dd><dt><a name="opt.narenas"></a><span class="term"> + + "<code class="mallctl">opt.narenas</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Maximum number of arenas to use for automatic + multiplexing of threads and arenas. The default is four times the + number of CPUs, or one if there is a single CPU.</p></dd><dt><a name="opt.lg_dirty_mult"></a><span class="term"> + + "<code class="mallctl">opt.lg_dirty_mult</code>" + + (<span class="type">ssize_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Per-arena minimum ratio (log base 2) of active to dirty + pages. Some dirty unused pages may be allowed to accumulate, within + the limit set by the ratio (or one chunk worth of dirty pages, + whichever is greater), before informing the kernel about some of those + pages via <span class="citerefentry"><span class="refentrytitle">madvise</span>(2)</span> or a similar system call. This + provides the kernel with sufficient information to recycle dirty pages + if physical memory becomes scarce and the pages remain unused. The + default minimum ratio is 8:1 (2^3:1); an option value of -1 will + disable dirty page purging.</p></dd><dt><a name="opt.stats_print"></a><span class="term"> + + "<code class="mallctl">opt.stats_print</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Enable/disable statistics printing at exit. If + enabled, the <code class="function">malloc_stats_print</code>(<em class="parameter"><code></code></em>) + function is called at program exit via an + <span class="citerefentry"><span class="refentrytitle">atexit</span>(3)</span> function. If + <code class="option">--enable-stats</code> is specified during configuration, this + has the potential to cause deadlock for a multi-threaded process that + exits while one or more threads are executing in the memory allocation + functions. Therefore, this option should only be used with care; it is + primarily intended as a performance tuning aid during application + development. This option is disabled by default.</p></dd><dt><a name="opt.junk"></a><span class="term"> + + "<code class="mallctl">opt.junk</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-fill</code>] + </span></dt><dd><p>Junk filling enabled/disabled. If enabled, each byte + of uninitialized allocated memory will be initialized to + <code class="literal">0xa5</code>. All deallocated memory will be initialized to + <code class="literal">0x5a</code>. This is intended for debugging and will + impact performance negatively. This option is disabled by default + unless <code class="option">--enable-debug</code> is specified during + configuration, in which case it is enabled by default unless running + inside <a class="ulink" href="http://valgrind.org/" target="_top">Valgrind</a>.</p></dd><dt><a name="opt.quarantine"></a><span class="term"> + + "<code class="mallctl">opt.quarantine</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-fill</code>] + </span></dt><dd><p>Per thread quarantine size in bytes. If non-zero, each + thread maintains a FIFO object quarantine that stores up to the + specified number of bytes of memory. The quarantined memory is not + freed until it is released from quarantine, though it is immediately + junk-filled if the <a class="link" href="#opt.junk"> + "<code class="mallctl">opt.junk</code>" + </a> option is + enabled. This feature is of particular use in combination with <a class="ulink" href="http://valgrind.org/" target="_top">Valgrind</a>, which can detect attempts + to access quarantined objects. This is intended for debugging and will + impact performance negatively. The default quarantine size is 0 unless + running inside Valgrind, in which case the default is 16 + MiB.</p></dd><dt><a name="opt.redzone"></a><span class="term"> + + "<code class="mallctl">opt.redzone</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-fill</code>] + </span></dt><dd><p>Redzones enabled/disabled. If enabled, small + allocations have redzones before and after them. Furthermore, if the + <a class="link" href="#opt.junk"> + "<code class="mallctl">opt.junk</code>" + </a> option is + enabled, the redzones are checked for corruption during deallocation. + However, the primary intended purpose of this feature is to be used in + combination with <a class="ulink" href="http://valgrind.org/" target="_top">Valgrind</a>, + which needs redzones in order to do effective buffer overflow/underflow + detection. This option is intended for debugging and will impact + performance negatively. This option is disabled by + default unless running inside Valgrind.</p></dd><dt><a name="opt.zero"></a><span class="term"> + + "<code class="mallctl">opt.zero</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-fill</code>] + </span></dt><dd><p>Zero filling enabled/disabled. If enabled, each byte + of uninitialized allocated memory will be initialized to 0. Note that + this initialization only happens once for each byte, so + <code class="function">realloc</code>(<em class="parameter"><code></code></em>) and + <code class="function">rallocm</code>(<em class="parameter"><code></code></em>) calls do not zero memory that + was previously allocated. This is intended for debugging and will + impact performance negatively. This option is disabled by default. + </p></dd><dt><a name="opt.utrace"></a><span class="term"> + + "<code class="mallctl">opt.utrace</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-utrace</code>] + </span></dt><dd><p>Allocation tracing based on + <span class="citerefentry"><span class="refentrytitle">utrace</span>(2)</span> enabled/disabled. This option + is disabled by default.</p></dd><dt><a name="opt.valgrind"></a><span class="term"> + + "<code class="mallctl">opt.valgrind</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-valgrind</code>] + </span></dt><dd><p><a class="ulink" href="http://valgrind.org/" target="_top">Valgrind</a> + support enabled/disabled. This option is vestigal because jemalloc + auto-detects whether it is running inside Valgrind. This option is + disabled by default, unless running inside Valgrind.</p></dd><dt><a name="opt.xmalloc"></a><span class="term"> + + "<code class="mallctl">opt.xmalloc</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-xmalloc</code>] + </span></dt><dd><p>Abort-on-out-of-memory enabled/disabled. If enabled, + rather than returning failure for any allocation function, display a + diagnostic message on <code class="constant">STDERR_FILENO</code> and cause the + program to drop core (using + <span class="citerefentry"><span class="refentrytitle">abort</span>(3)</span>). If an application is + designed to depend on this behavior, set the option at compile time by + including the following in the source code: + </p><pre class="programlisting"> +malloc_conf = "xmalloc:true";</pre><p> + This option is disabled by default.</p></dd><dt><a name="opt.tcache"></a><span class="term"> + + "<code class="mallctl">opt.tcache</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-tcache</code>] + </span></dt><dd><p>Thread-specific caching enabled/disabled. When there + are multiple threads, each thread uses a thread-specific cache for + objects up to a certain size. Thread-specific caching allows many + allocations to be satisfied without performing any thread + synchronization, at the cost of increased memory use. See the + <a class="link" href="#opt.lg_tcache_max"> + "<code class="mallctl">opt.lg_tcache_max</code>" + </a> + option for related tuning information. This option is enabled by + default unless running inside <a class="ulink" href="http://valgrind.org/" target="_top">Valgrind</a>.</p></dd><dt><a name="opt.lg_tcache_max"></a><span class="term"> + + "<code class="mallctl">opt.lg_tcache_max</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-tcache</code>] + </span></dt><dd><p>Maximum size class (log base 2) to cache in the + thread-specific cache. At a minimum, all small size classes are + cached, and at a maximum all large size classes are cached. The + default maximum is 32 KiB (2^15).</p></dd><dt><a name="opt.prof"></a><span class="term"> + + "<code class="mallctl">opt.prof</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Memory profiling enabled/disabled. If enabled, profile + memory allocation activity. See the <a class="link" href="#opt.prof_active"> + "<code class="mallctl">opt.prof_active</code>" + </a> + option for on-the-fly activation/deactivation. See the <a class="link" href="#opt.lg_prof_sample"> + "<code class="mallctl">opt.lg_prof_sample</code>" + </a> + option for probabilistic sampling control. See the <a class="link" href="#opt.prof_accum"> + "<code class="mallctl">opt.prof_accum</code>" + </a> + option for control of cumulative sample reporting. See the <a class="link" href="#opt.lg_prof_interval"> + "<code class="mallctl">opt.lg_prof_interval</code>" + </a> + option for information on interval-triggered profile dumping, the <a class="link" href="#opt.prof_gdump"> + "<code class="mallctl">opt.prof_gdump</code>" + </a> + option for information on high-water-triggered profile dumping, and the + <a class="link" href="#opt.prof_final"> + "<code class="mallctl">opt.prof_final</code>" + </a> + option for final profile dumping. Profile output is compatible with + the included <span class="command"><strong>pprof</strong></span> Perl script, which originates + from the <a class="ulink" href="http://code.google.com/p/gperftools/" target="_top">gperftools + package</a>.</p></dd><dt><a name="opt.prof_prefix"></a><span class="term"> + + "<code class="mallctl">opt.prof_prefix</code>" + + (<span class="type">const char *</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Filename prefix for profile dumps. If the prefix is + set to the empty string, no automatic dumps will occur; this is + primarily useful for disabling the automatic final heap dump (which + also disables leak reporting, if enabled). The default prefix is + <code class="filename">jeprof</code>.</p></dd><dt><a name="opt.prof_active"></a><span class="term"> + + "<code class="mallctl">opt.prof_active</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Profiling activated/deactivated. This is a secondary + control mechanism that makes it possible to start the application with + profiling enabled (see the <a class="link" href="#opt.prof"> + "<code class="mallctl">opt.prof</code>" + </a> option) but + inactive, then toggle profiling at any time during program execution + with the <a class="link" href="#prof.active"> + "<code class="mallctl">prof.active</code>" + </a> mallctl. + This option is enabled by default.</p></dd><dt><a name="opt.lg_prof_sample"></a><span class="term"> + + "<code class="mallctl">opt.lg_prof_sample</code>" + + (<span class="type">ssize_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Average interval (log base 2) between allocation + samples, as measured in bytes of allocation activity. Increasing the + sampling interval decreases profile fidelity, but also decreases the + computational overhead. The default sample interval is 512 KiB (2^19 + B).</p></dd><dt><a name="opt.prof_accum"></a><span class="term"> + + "<code class="mallctl">opt.prof_accum</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Reporting of cumulative object/byte counts in profile + dumps enabled/disabled. If this option is enabled, every unique + backtrace must be stored for the duration of execution. Depending on + the application, this can impose a large memory overhead, and the + cumulative counts are not always of interest. This option is disabled + by default.</p></dd><dt><a name="opt.lg_prof_interval"></a><span class="term"> + + "<code class="mallctl">opt.lg_prof_interval</code>" + + (<span class="type">ssize_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Average interval (log base 2) between memory profile + dumps, as measured in bytes of allocation activity. The actual + interval between dumps may be sporadic because decentralized allocation + counters are used to avoid synchronization bottlenecks. Profiles are + dumped to files named according to the pattern + <code class="filename"><prefix>.<pid>.<seq>.i<iseq>.heap</code>, + where <code class="literal"><prefix></code> is controlled by the + <a class="link" href="#opt.prof_prefix"> + "<code class="mallctl">opt.prof_prefix</code>" + </a> + option. By default, interval-triggered profile dumping is disabled + (encoded as -1). + </p></dd><dt><a name="opt.prof_gdump"></a><span class="term"> + + "<code class="mallctl">opt.prof_gdump</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Trigger a memory profile dump every time the total + virtual memory exceeds the previous maximum. Profiles are dumped to + files named according to the pattern + <code class="filename"><prefix>.<pid>.<seq>.u<useq>.heap</code>, + where <code class="literal"><prefix></code> is controlled by the <a class="link" href="#opt.prof_prefix"> + "<code class="mallctl">opt.prof_prefix</code>" + </a> + option. This option is disabled by default.</p></dd><dt><a name="opt.prof_final"></a><span class="term"> + + "<code class="mallctl">opt.prof_final</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Use an + <span class="citerefentry"><span class="refentrytitle">atexit</span>(3)</span> function to dump final memory + usage to a file named according to the pattern + <code class="filename"><prefix>.<pid>.<seq>.f.heap</code>, + where <code class="literal"><prefix></code> is controlled by the <a class="link" href="#opt.prof_prefix"> + "<code class="mallctl">opt.prof_prefix</code>" + </a> + option. This option is enabled by default.</p></dd><dt><a name="opt.prof_leak"></a><span class="term"> + + "<code class="mallctl">opt.prof_leak</code>" + + (<span class="type">bool</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Leak reporting enabled/disabled. If enabled, use an + <span class="citerefentry"><span class="refentrytitle">atexit</span>(3)</span> function to report memory leaks + detected by allocation sampling. See the + <a class="link" href="#opt.prof"> + "<code class="mallctl">opt.prof</code>" + </a> option for + information on analyzing heap profile output. This option is disabled + by default.</p></dd><dt><span class="term"> + + "<code class="mallctl">thread.arena</code>" + + (<span class="type">unsigned</span>) + <code class="literal">rw</code> + </span></dt><dd><p>Get or set the arena associated with the calling + thread. If the specified arena was not initialized beforehand (see the + <a class="link" href="#arenas.initialized"> + "<code class="mallctl">arenas.initialized</code>" + </a> + mallctl), it will be automatically initialized as a side effect of + calling this interface.</p></dd><dt><a name="thread.allocated"></a><span class="term"> + + "<code class="mallctl">thread.allocated</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Get the total number of bytes ever allocated by the + calling thread. This counter has the potential to wrap around; it is + up to the application to appropriately interpret the counter in such + cases.</p></dd><dt><span class="term"> + + "<code class="mallctl">thread.allocatedp</code>" + + (<span class="type">uint64_t *</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Get a pointer to the the value that is returned by the + <a class="link" href="#thread.allocated"> + "<code class="mallctl">thread.allocated</code>" + </a> + mallctl. This is useful for avoiding the overhead of repeated + <code class="function">mallctl*</code>(<em class="parameter"><code></code></em>) calls.</p></dd><dt><a name="thread.deallocated"></a><span class="term"> + + "<code class="mallctl">thread.deallocated</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Get the total number of bytes ever deallocated by the + calling thread. This counter has the potential to wrap around; it is + up to the application to appropriately interpret the counter in such + cases.</p></dd><dt><span class="term"> + + "<code class="mallctl">thread.deallocatedp</code>" + + (<span class="type">uint64_t *</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Get a pointer to the the value that is returned by the + <a class="link" href="#thread.deallocated"> + "<code class="mallctl">thread.deallocated</code>" + </a> + mallctl. This is useful for avoiding the overhead of repeated + <code class="function">mallctl*</code>(<em class="parameter"><code></code></em>) calls.</p></dd><dt><span class="term"> + + "<code class="mallctl">thread.tcache.enabled</code>" + + (<span class="type">bool</span>) + <code class="literal">rw</code> + [<code class="option">--enable-tcache</code>] + </span></dt><dd><p>Enable/disable calling thread's tcache. The tcache is + implicitly flushed as a side effect of becoming + disabled (see + "<code class="mallctl">thread.tcache.flush</code>" + ). + </p></dd><dt><span class="term"> + + "<code class="mallctl">thread.tcache.flush</code>" + + (<span class="type">void</span>) + <code class="literal">--</code> + [<code class="option">--enable-tcache</code>] + </span></dt><dd><p>Flush calling thread's tcache. This interface releases + all cached objects and internal data structures associated with the + calling thread's thread-specific cache. Ordinarily, this interface + need not be called, since automatic periodic incremental garbage + collection occurs, and the thread cache is automatically discarded when + a thread exits. However, garbage collection is triggered by allocation + activity, so it is possible for a thread that stops + allocating/deallocating to retain its cache indefinitely, in which case + the developer may find manual flushing useful.</p></dd><dt><a name="arena.i.purge"></a><span class="term"> + + "<code class="mallctl">arena.<i>.purge</code>" + + (<span class="type">unsigned</span>) + <code class="literal">--</code> + </span></dt><dd><p>Purge unused dirty pages for arena <i>, or for + all arenas if <i> equals <a class="link" href="#arenas.narenas"> + "<code class="mallctl">arenas.narenas</code>" + </a>. + </p></dd><dt><a name="arena.i.dss"></a><span class="term"> + + "<code class="mallctl">arena.<i>.dss</code>" + + (<span class="type">const char *</span>) + <code class="literal">rw</code> + </span></dt><dd><p>Set the precedence of dss allocation as related to mmap + allocation for arena <i>, or for all arenas if <i> equals + <a class="link" href="#arenas.narenas"> + "<code class="mallctl">arenas.narenas</code>" + </a>. See + <a class="link" href="#opt.dss"> + "<code class="mallctl">opt.dss</code>" + </a> for supported + settings. + </p></dd><dt><a name="arenas.narenas"></a><span class="term"> + + "<code class="mallctl">arenas.narenas</code>" + + (<span class="type">unsigned</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Current limit on number of arenas.</p></dd><dt><a name="arenas.initialized"></a><span class="term"> + + "<code class="mallctl">arenas.initialized</code>" + + (<span class="type">bool *</span>) + <code class="literal">r-</code> + </span></dt><dd><p>An array of <a class="link" href="#arenas.narenas"> + "<code class="mallctl">arenas.narenas</code>" + </a> + booleans. Each boolean indicates whether the corresponding arena is + initialized.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.quantum</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Quantum size.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.page</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Page size.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.tcache_max</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-tcache</code>] + </span></dt><dd><p>Maximum thread-cached size class.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.nbins</code>" + + (<span class="type">unsigned</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Number of bin size classes.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.nhbins</code>" + + (<span class="type">unsigned</span>) + <code class="literal">r-</code> + [<code class="option">--enable-tcache</code>] + </span></dt><dd><p>Total number of thread cache bin size + classes.</p></dd><dt><a name="arenas.bin.i.size"></a><span class="term"> + + "<code class="mallctl">arenas.bin.<i>.size</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Maximum size supported by size class.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.bin.<i>.nregs</code>" + + (<span class="type">uint32_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Number of regions per page run.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.bin.<i>.run_size</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Number of bytes per page run.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.nlruns</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Total number of large size classes.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.lrun.<i>.size</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Maximum size supported by this large size + class.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.purge</code>" + + (<span class="type">unsigned</span>) + <code class="literal">-w</code> + </span></dt><dd><p>Purge unused dirty pages for the specified arena, or + for all arenas if none is specified.</p></dd><dt><span class="term"> + + "<code class="mallctl">arenas.extend</code>" + + (<span class="type">unsigned</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Extend the array of arenas by appending a new arena, + and returning the new arena index.</p></dd><dt><a name="prof.active"></a><span class="term"> + + "<code class="mallctl">prof.active</code>" + + (<span class="type">bool</span>) + <code class="literal">rw</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Control whether sampling is currently active. See the + <a class="link" href="#opt.prof_active"> + "<code class="mallctl">opt.prof_active</code>" + </a> + option for additional information. + </p></dd><dt><span class="term"> + + "<code class="mallctl">prof.dump</code>" + + (<span class="type">const char *</span>) + <code class="literal">-w</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Dump a memory profile to the specified file, or if NULL + is specified, to a file according to the pattern + <code class="filename"><prefix>.<pid>.<seq>.m<mseq>.heap</code>, + where <code class="literal"><prefix></code> is controlled by the + <a class="link" href="#opt.prof_prefix"> + "<code class="mallctl">opt.prof_prefix</code>" + </a> + option.</p></dd><dt><span class="term"> + + "<code class="mallctl">prof.interval</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-prof</code>] + </span></dt><dd><p>Average number of bytes allocated between + inverval-based profile dumps. See the + <a class="link" href="#opt.lg_prof_interval"> + "<code class="mallctl">opt.lg_prof_interval</code>" + </a> + option for additional information.</p></dd><dt><a name="stats.cactive"></a><span class="term"> + + "<code class="mallctl">stats.cactive</code>" + + (<span class="type">size_t *</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Pointer to a counter that contains an approximate count + of the current number of bytes in active pages. The estimate may be + high, but never low, because each arena rounds up to the nearest + multiple of the chunk size when computing its contribution to the + counter. Note that the <a class="link" href="#epoch"> + "<code class="mallctl">epoch</code>" + </a> mallctl has no bearing + on this counter. Furthermore, counter consistency is maintained via + atomic operations, so it is necessary to use an atomic operation in + order to guarantee a consistent read when dereferencing the pointer. + </p></dd><dt><a name="stats.allocated"></a><span class="term"> + + "<code class="mallctl">stats.allocated</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Total number of bytes allocated by the + application.</p></dd><dt><a name="stats.active"></a><span class="term"> + + "<code class="mallctl">stats.active</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Total number of bytes in active pages allocated by the + application. This is a multiple of the page size, and greater than or + equal to <a class="link" href="#stats.allocated"> + "<code class="mallctl">stats.allocated</code>" + </a>. + This does not include <a class="link" href="#stats.arenas.i.pdirty"> + + "<code class="mallctl">stats.arenas.<i>.pdirty</code>" + </a> and pages + entirely devoted to allocator metadata.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.mapped</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Total number of bytes in chunks mapped on behalf of the + application. This is a multiple of the chunk size, and is at least as + large as <a class="link" href="#stats.active"> + "<code class="mallctl">stats.active</code>" + </a>. This + does not include inactive chunks.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.chunks.current</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Total number of chunks actively mapped on behalf of the + application. This does not include inactive chunks. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.chunks.total</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of chunks allocated.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.chunks.high</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Maximum number of active chunks at any time thus far. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.huge.allocated</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Number of bytes currently allocated by huge objects. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.huge.nmalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of huge allocation requests. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.huge.ndalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of huge deallocation requests. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.dss</code>" + + (<span class="type">const char *</span>) + <code class="literal">r-</code> + </span></dt><dd><p>dss (<span class="citerefentry"><span class="refentrytitle">sbrk</span>(2)</span>) allocation precedence as + related to <span class="citerefentry"><span class="refentrytitle">mmap</span>(2)</span> allocation. See <a class="link" href="#opt.dss"> + "<code class="mallctl">opt.dss</code>" + </a> for details. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.nthreads</code>" + + (<span class="type">unsigned</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Number of threads currently assigned to + arena.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.pactive</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Number of pages in active runs.</p></dd><dt><a name="stats.arenas.i.pdirty"></a><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.pdirty</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + </span></dt><dd><p>Number of pages within unused runs that are potentially + dirty, and for which <code class="function">madvise</code>(<em class="parameter"><code>...</code></em>, + <em class="parameter"><code><code class="constant">MADV_DONTNEED</code></code></em>) or + similar has not been called.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.mapped</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Number of mapped bytes.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.npurge</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Number of dirty page purge sweeps performed. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.nmadvise</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Number of <code class="function">madvise</code>(<em class="parameter"><code>...</code></em>, + <em class="parameter"><code><code class="constant">MADV_DONTNEED</code></code></em>) or + similar calls made to purge dirty pages.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.npurged</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Number of pages purged.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.small.allocated</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Number of bytes currently allocated by small objects. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.small.nmalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of allocation requests served by + small bins.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.small.ndalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of small objects returned to bins. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.small.nrequests</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of small allocation requests. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.large.allocated</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Number of bytes currently allocated by large objects. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.large.nmalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of large allocation requests served + directly by the arena.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.large.ndalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of large deallocation requests served + directly by the arena.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.large.nrequests</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of large allocation requests. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.allocated</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Current number of bytes allocated by + bin.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.nmalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of allocations served by bin. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.ndalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of allocations returned to bin. + </p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.nrequests</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of allocation + requests.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.nfills</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code> <code class="option">--enable-tcache</code>] + </span></dt><dd><p>Cumulative number of tcache fills.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.nflushes</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code> <code class="option">--enable-tcache</code>] + </span></dt><dd><p>Cumulative number of tcache flushes.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.nruns</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of runs created.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.nreruns</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of times the current run from which + to allocate changed.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.bins.<j>.curruns</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Current number of runs.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.lruns.<j>.nmalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of allocation requests for this size + class served directly by the arena.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.lruns.<j>.ndalloc</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of deallocation requests for this + size class served directly by the arena.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.lruns.<j>.nrequests</code>" + + (<span class="type">uint64_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Cumulative number of allocation requests for this size + class.</p></dd><dt><span class="term"> + + "<code class="mallctl">stats.arenas.<i>.lruns.<j>.curruns</code>" + + (<span class="type">size_t</span>) + <code class="literal">r-</code> + [<code class="option">--enable-stats</code>] + </span></dt><dd><p>Current number of runs for this size class. + </p></dd></dl></div></div><div class="refsect1" title="DEBUGGING MALLOC PROBLEMS"><a name="debugging_malloc_problems"></a><h2>DEBUGGING MALLOC PROBLEMS</h2><p>When debugging, it is a good idea to configure/build jemalloc with + the <code class="option">--enable-debug</code> and <code class="option">--enable-fill</code> + options, and recompile the program with suitable options and symbols for + debugger support. When so configured, jemalloc incorporates a wide variety + of run-time assertions that catch application errors such as double-free, + write-after-free, etc.</p><p>Programs often accidentally depend on “uninitialized” + memory actually being filled with zero bytes. Junk filling + (see the <a class="link" href="#opt.junk"> + "<code class="mallctl">opt.junk</code>" + </a> + option) tends to expose such bugs in the form of obviously incorrect + results and/or coredumps. Conversely, zero + filling (see the <a class="link" href="#opt.zero"> + "<code class="mallctl">opt.zero</code>" + </a> option) eliminates + the symptoms of such bugs. Between these two options, it is usually + possible to quickly detect, diagnose, and eliminate such bugs.</p><p>This implementation does not provide much detail about the problems + it detects, because the performance impact for storing such information + would be prohibitive. However, jemalloc does integrate with the most + excellent <a class="ulink" href="http://valgrind.org/" target="_top">Valgrind</a> tool if the + <code class="option">--enable-valgrind</code> configuration option is enabled.</p></div><div class="refsect1" title="DIAGNOSTIC MESSAGES"><a name="diagnostic_messages"></a><h2>DIAGNOSTIC MESSAGES</h2><p>If any of the memory allocation/deallocation functions detect an + error or warning condition, a message will be printed to file descriptor + <code class="constant">STDERR_FILENO</code>. Errors will result in the process + dumping core. If the <a class="link" href="#opt.abort"> + "<code class="mallctl">opt.abort</code>" + </a> option is set, most + warnings are treated as errors.</p><p>The <code class="varname">malloc_message</code> variable allows the programmer + to override the function which emits the text strings forming the errors + and warnings if for some reason the <code class="constant">STDERR_FILENO</code> file + descriptor is not suitable for this. + <code class="function">malloc_message</code>(<em class="parameter"><code></code></em>) takes the + <em class="parameter"><code>cbopaque</code></em> pointer argument that is + <code class="constant">NULL</code> unless overridden by the arguments in a call to + <code class="function">malloc_stats_print</code>(<em class="parameter"><code></code></em>), followed by a string + pointer. Please note that doing anything which tries to allocate memory in + this function is likely to result in a crash or deadlock.</p><p>All messages are prefixed by + “<code class="computeroutput"><jemalloc>: </code>”.</p></div><div class="refsect1" title="RETURN VALUES"><a name="return_values"></a><h2>RETURN VALUES</h2><div class="refsect2" title="Standard API"><a name="id286954473"></a><h3>Standard API</h3><p>The <code class="function">malloc</code>(<em class="parameter"><code></code></em>) and + <code class="function">calloc</code>(<em class="parameter"><code></code></em>) functions return a pointer to the + allocated memory if successful; otherwise a <code class="constant">NULL</code> + pointer is returned and <code class="varname">errno</code> is set to + <span class="errorname">ENOMEM</span>.</p><p>The <code class="function">posix_memalign</code>(<em class="parameter"><code></code></em>) function + returns the value 0 if successful; otherwise it returns an error value. + The <code class="function">posix_memalign</code>(<em class="parameter"><code></code></em>) function will fail + if: + </p><div class="variablelist"><dl><dt><span class="term"><span class="errorname">EINVAL</span></span></dt><dd><p>The <em class="parameter"><code>alignment</code></em> parameter is + not a power of 2 at least as large as + <code class="code">sizeof(<span class="type">void *</span>)</code>. + </p></dd><dt><span class="term"><span class="errorname">ENOMEM</span></span></dt><dd><p>Memory allocation error.</p></dd></dl></div><p> + </p><p>The <code class="function">aligned_alloc</code>(<em class="parameter"><code></code></em>) function returns + a pointer to the allocated memory if successful; otherwise a + <code class="constant">NULL</code> pointer is returned and + <code class="varname">errno</code> is set. The + <code class="function">aligned_alloc</code>(<em class="parameter"><code></code></em>) function will fail if: + </p><div class="variablelist"><dl><dt><span class="term"><span class="errorname">EINVAL</span></span></dt><dd><p>The <em class="parameter"><code>alignment</code></em> parameter is + not a power of 2. + </p></dd><dt><span class="term"><span class="errorname">ENOMEM</span></span></dt><dd><p>Memory allocation error.</p></dd></dl></div><p> + </p><p>The <code class="function">realloc</code>(<em class="parameter"><code></code></em>) function returns a + pointer, possibly identical to <em class="parameter"><code>ptr</code></em>, to the + allocated memory if successful; otherwise a <code class="constant">NULL</code> + pointer is returned, and <code class="varname">errno</code> is set to + <span class="errorname">ENOMEM</span> if the error was the result of an + allocation failure. The <code class="function">realloc</code>(<em class="parameter"><code></code></em>) + function always leaves the original buffer intact when an error occurs. + </p><p>The <code class="function">free</code>(<em class="parameter"><code></code></em>) function returns no + value.</p></div><div class="refsect2" title="Non-standard API"><a name="id286954690"></a><h3>Non-standard API</h3><p>The <code class="function">malloc_usable_size</code>(<em class="parameter"><code></code></em>) function + returns the usable size of the allocation pointed to by + <em class="parameter"><code>ptr</code></em>. </p><p>The <code class="function">mallctl</code>(<em class="parameter"><code></code></em>), + <code class="function">mallctlnametomib</code>(<em class="parameter"><code></code></em>), and + <code class="function">mallctlbymib</code>(<em class="parameter"><code></code></em>) functions return 0 on + success; otherwise they return an error value. The functions will fail + if: + </p><div class="variablelist"><dl><dt><span class="term"><span class="errorname">EINVAL</span></span></dt><dd><p><em class="parameter"><code>newp</code></em> is not + <code class="constant">NULL</code>, and <em class="parameter"><code>newlen</code></em> is too + large or too small. Alternatively, <em class="parameter"><code>*oldlenp</code></em> + is too large or too small; in this case as much data as possible + are read despite the error.</p></dd><dt><span class="term"><span class="errorname">ENOMEM</span></span></dt><dd><p><em class="parameter"><code>*oldlenp</code></em> is too short to + hold the requested value.</p></dd><dt><span class="term"><span class="errorname">ENOENT</span></span></dt><dd><p><em class="parameter"><code>name</code></em> or + <em class="parameter"><code>mib</code></em> specifies an unknown/invalid + value.</p></dd><dt><span class="term"><span class="errorname">EPERM</span></span></dt><dd><p>Attempt to read or write void value, or attempt to + write read-only value.</p></dd><dt><span class="term"><span class="errorname">EAGAIN</span></span></dt><dd><p>A memory allocation failure + occurred.</p></dd><dt><span class="term"><span class="errorname">EFAULT</span></span></dt><dd><p>An interface with side effects failed in some way + not directly related to <code class="function">mallctl*</code>(<em class="parameter"><code></code></em>) + read/write processing.</p></dd></dl></div><p> + </p></div><div class="refsect2" title="Experimental API"><a name="id286954842"></a><h3>Experimental API</h3><p>The <code class="function">allocm</code>(<em class="parameter"><code></code></em>), + <code class="function">rallocm</code>(<em class="parameter"><code></code></em>), + <code class="function">sallocm</code>(<em class="parameter"><code></code></em>), + <code class="function">dallocm</code>(<em class="parameter"><code></code></em>), and + <code class="function">nallocm</code>(<em class="parameter"><code></code></em>) functions return + <code class="constant">ALLOCM_SUCCESS</code> on success; otherwise they return an + error value. The <code class="function">allocm</code>(<em class="parameter"><code></code></em>), + <code class="function">rallocm</code>(<em class="parameter"><code></code></em>), and + <code class="function">nallocm</code>(<em class="parameter"><code></code></em>) functions will fail if: + </p><div class="variablelist"><dl><dt><span class="term"><span class="errorname">ALLOCM_ERR_OOM</span></span></dt><dd><p>Out of memory. Insufficient contiguous memory was + available to service the allocation request. The + <code class="function">allocm</code>(<em class="parameter"><code></code></em>) function additionally sets + <em class="parameter"><code>*ptr</code></em> to <code class="constant">NULL</code>, whereas + the <code class="function">rallocm</code>(<em class="parameter"><code></code></em>) function leaves + <code class="constant">*ptr</code> unmodified.</p></dd></dl></div><p> + The <code class="function">rallocm</code>(<em class="parameter"><code></code></em>) function will also + fail if: + </p><div class="variablelist"><dl><dt><span class="term"><span class="errorname">ALLOCM_ERR_NOT_MOVED</span></span></dt><dd><p><code class="constant">ALLOCM_NO_MOVE</code> was specified, + but the reallocation request could not be serviced without moving + the object.</p></dd></dl></div><p> + </p></div></div><div class="refsect1" title="ENVIRONMENT"><a name="environment"></a><h2>ENVIRONMENT</h2><p>The following environment variable affects the execution of the + allocation functions: + </p><div class="variablelist"><dl><dt><span class="term"><code class="envar">MALLOC_CONF</code></span></dt><dd><p>If the environment variable + <code class="envar">MALLOC_CONF</code> is set, the characters it contains + will be interpreted as options.</p></dd></dl></div><p> + </p></div><div class="refsect1" title="EXAMPLES"><a name="examples"></a><h2>EXAMPLES</h2><p>To dump core whenever a problem occurs: + </p><pre class="screen">ln -s 'abort:true' /etc/malloc.conf</pre><p> + </p><p>To specify in the source a chunk size that is 16 MiB: + </p><pre class="programlisting"> +malloc_conf = "lg_chunk:24";</pre></div><div class="refsect1" title="SEE ALSO"><a name="see_also"></a><h2>SEE ALSO</h2><p><span class="citerefentry"><span class="refentrytitle">madvise</span>(2)</span>, + <span class="citerefentry"><span class="refentrytitle">mmap</span>(2)</span>, + <span class="citerefentry"><span class="refentrytitle">sbrk</span>(2)</span>, + <span class="citerefentry"><span class="refentrytitle">utrace</span>(2)</span>, + <span class="citerefentry"><span class="refentrytitle">alloca</span>(3)</span>, + <span class="citerefentry"><span class="refentrytitle">atexit</span>(3)</span>, + <span class="citerefentry"><span class="refentrytitle">getpagesize</span>(3)</span></p></div><div class="refsect1" title="STANDARDS"><a name="standards"></a><h2>STANDARDS</h2><p>The <code class="function">malloc</code>(<em class="parameter"><code></code></em>), + <code class="function">calloc</code>(<em class="parameter"><code></code></em>), + <code class="function">realloc</code>(<em class="parameter"><code></code></em>), and + <code class="function">free</code>(<em class="parameter"><code></code></em>) functions conform to ISO/IEC + 9899:1990 (“ISO C90”).</p><p>The <code class="function">posix_memalign</code>(<em class="parameter"><code></code></em>) function conforms + to IEEE Std 1003.1-2001 (“POSIX.1”).</p></div></div></body></html> |