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Diffstat (limited to 'ext/Thread/README.threads')
| -rw-r--r-- | ext/Thread/README.threads | 331 |
1 files changed, 4 insertions, 327 deletions
diff --git a/ext/Thread/README.threads b/ext/Thread/README.threads index 9cd0dbcb20..6e4d13344b 100644 --- a/ext/Thread/README.threads +++ b/ext/Thread/README.threads @@ -7,333 +7,7 @@ available only internally and to XS extension builders, and used by the Win32 port for emulating fork()). As of Perl 5.8.0, ithreads has become the standard threading model for Perl. -If you really want the older support for threads described below, -it is enabled with: - - sh Configure -Dusethreads -Duse5005threads - -Be warned that the old 5.005 implementation of threads is known -to be quite buggy, and unmaintained, which means that the bugs -are there to stay. (We are not mean by not fixing the bugs: -the bugs are just really, really, really hard to fix. Honest.) - -The rest of this document only applies to the use5005threads style of -threads, and the comments on what works on which platform are highly -obsolete and preserved here for archaeology buffs only. The -architecture specific hints files do all the necessary option -tweaking automatically during Configure, both for the 5.005 threads -and for the new interpreter threads. - ---------------------------------------------------------------------------- - -Support for threading is still in the highly experimental stages. There -are known race conditions that show up under high contention on SMP -machines. Internal implementation is still subject to changes. -It is not recommended for production use at this time. - ---------------------------------------------------------------------------- - -Building - -If your system is in the following list you should be able to just: - - ./Configure -Dusethreads -Duse5005threads -des - make - -and ignore the rest of this "Building" section. If not, continue -from the "Problems" section. - - * Linux 2.* (with the LinuxThreads library installed: - that's the linuxthreads and linuxthreads-devel RPMs - for RedHat) - - * Tru64 UNIX (formerly Digital UNIX formerly DEC OSF/1) - (see additional note below) - - * Solaris 2.* for recentish x (2.5 is OK) - - * IRIX 6.2 or newer. 6.2 will require a few OS patches. - IMPORTANT: Without patch 2401 (or its replacement), - a kernel bug in IRIX 6.2 will cause your machine to - panic and crash when running threaded perl. - IRIX 6.3 and up should be OK. See lower down for patch details. - - * AIX 4.1.5 or newer. - - * FreeBSD 2.2.8 or newer. - - * OpenBSD - - * NeXTstep, OpenStep - - * OS/2 - - * DOS DJGPP - - * VM/ESA - ---------------------------------------------------------------------------- - -Problems - -If the simple way doesn't work or you are using another platform which -you believe supports POSIX.1c threads then read on. Additional -information may be in a platform-specific "hints" file in the hints/ -subdirectory. - -On platforms that use Configure to build perl, omit the -d from your -./Configure arguments. For example, use: - - ./Configure -Dusethreads -Duse5005threads - -When Configure prompts you for ccflags, insert any other arguments in -there that your compiler needs to use POSIX threads (-D_REENTRANT, --pthreads, -threads, -pthread, -thread, are good guesses). When -Configure prompts you for linking flags, include any flags required -for threading (usually nothing special is required here). Finally, -when Configure prompts you for libraries, include any necessary -libraries (e.g. -lpthread). Pay attention to the order of libraries. -It is probably necessary to specify your threading library *before* -your standard C library, e.g. it might be necessary to have -lpthread --lc, instead of -lc -lpthread. You may also need to use -lc_r instead -of -lc. - -Once you have specified all your compiler flags, you can have Configure -accept all the defaults for the remainder of the session by typing &-d -at any Configure prompt. - -Some additional notes (some of these may be obsolete now, other items -may be handled automatically): - -For Digital Unix 4.x: - Add -pthread to ccflags - Add -pthread to ldflags - Add -lpthread -lc_r to lddlflags - - For some reason, the extra includes for pthreads make Digital UNIX - complain fatally about the sbrk() declaration in perl's malloc.c - so use the native malloc, e.g. sh Configure -Uusemymalloc, or - manually edit your config.sh as follows: - Change usemymalloc to n - Zap mallocobj and mallocsrc (foo='') - Change d_mymalloc to undef - -For Digital Unix 3.x (Formerly DEC OSF/1): - Add -DOLD_PTHREADS_API to ccflags - If compiling with the GNU cc compiler, remove -threads from ccflags - - (The following should be done automatically if you call Configure - with the -Dusethreads option). - Add -lpthread -lmach -lc_r to libs (in the order specified). - -For IRIX: - (This should all be done automatically by the hint file). - Add -lpthread to libs - For IRIX 6.2, you have to have the following patches installed: - 1404 Irix 6.2 Posix 1003.1b man pages - 1645 IRIX 6.2 & 6.3 POSIX header file updates - 2000 Irix 6.2 Posix 1003.1b support modules - 2254 Pthread library fixes - 2401 6.2 all platform kernel rollup - IMPORTANT: Without patch 2401, a kernel bug in IRIX 6.2 will - cause your machine to panic and crash when running threaded perl. - IRIX 6.3 and up should be OK. - - For IRIX 6.3 and 6.4 the pthreads should work out of the box. - Thanks to Hannu Napari <Hannu.Napari@hut.fi> for the IRIX - pthreads patches information. - -For AIX: - (This should all be done automatically by the hint file). - Change cc to xlc_r or cc_r. - Add -DNEED_PTHREAD_INIT to ccflags and cppflags - Add -lc_r to libswanted - Change -lc in lddflags to be -lpthread -lc_r -lc - -For Win32: - See README.win32, and the notes at the beginning of win32/Makefile - or win32/makefile.mk. - -Now you can do a - make - -When you succeed in compiling and testing ("make test" after your -build) a threaded Perl in a platform previously unknown to support -threaded perl, please let perlbug@perl.com know about your victory. -Explain what you did in painful detail. - ---------------------------------------------------------------------------- - -O/S specific bugs - -Irix 6.2: See the Irix warning above. - -LinuxThreads 0.5 has a bug which can cause file descriptor 0 to be -closed after a fork() leading to many strange symptoms. Version 0.6 -has this fixed but the following patch can be applied to 0.5 for now: - ------------------------------ cut here ----------------------------- ---- linuxthreads-0.5/pthread.c.ORI Mon Oct 6 13:55:50 1997 -+++ linuxthreads-0.5/pthread.c Mon Oct 6 13:57:24 1997 -@@ -312,8 +312,10 @@ - free(pthread_manager_thread_bos); - pthread_manager_thread_bos = pthread_manager_thread_tos = NULL; - /* Close the two ends of the pipe */ -- close(pthread_manager_request); -- close(pthread_manager_reader); -+ if (pthread_manager_request >= 0) { -+ close(pthread_manager_request); -+ close(pthread_manager_reader); -+ } - pthread_manager_request = pthread_manager_reader = -1; - /* Update the pid of the main thread */ - self->p_pid = getpid(); ------------------------------ cut here ----------------------------- - - -Building the Thread extension - -The Thread extension is now part of the main perl distribution tree. -If you did Configure -Dusethreads -Duse5005threads then it will have been -added to the list of extensions automatically. - -You can try some of the tests with - cd ext/Thread - perl create.t - perl join.t - perl lock.t - perl io.t -etc. -The io one leaves a thread reading from the keyboard on stdin so -as the ping messages appear you can type lines and see them echoed. - -Try running the main perl test suite too. There are known -failures for some of the DBM/DB extensions (if their underlying -libraries were not compiled to be thread-aware). - ---------------------------------------------------------------------------- - -Bugs - -* FAKE_THREADS should produce a working perl but the Thread -extension won't build with it yet. (FAKE_THREADS has not been -tested at all in recent times.) - -* There may still be races where bugs show up under contention. - ---------------------------------------------------------------------------- - -Debugging - -Use the -DS command-line option to turn on debugging of the -multi-threading code. Under Linux, that also turns on a quick -hack I did to grab a bit of extra information from segfaults. -If you have a fancier gdb/threads setup than I do then you'll -have to delete the lines in perl.c which say - #if defined(DEBUGGING) && defined(USE_5005THREADS) && defined(__linux__) - DEBUG_S(signal(SIGSEGV, (void(*)(int))catch_sigsegv);); - #endif - ---------------------------------------------------------------------------- - -Background - -Some old globals (e.g. stack_sp, op) and some old per-interpreter -variables (e.g. tmps_stack, cxstack) move into struct thread. -All fields of struct thread which derived from original perl -variables have names of the form Tfoo. For example, stack_sp becomes -the field Tstack_sp of struct thread. For those fields which moved -from original perl, thread.h does - #define foo (thr->Tfoo) -This means that all functions in perl which need to use one of these -fields need an (automatic) variable thr which points at the current -thread's struct thread. For pp_foo functions, it is passed around as -an argument, for other functions they do - dTHR; -which declares and initialises thr from thread-specific data -via pthread_getspecific. If a function fails to compile with an -error about "no such variable thr", it probably just needs a dTHR -at the top. - - -Fake threads - -For FAKE_THREADS, thr is a global variable and perl schedules threads -by altering thr in between appropriate ops. The next and prev fields -of struct thread keep all fake threads on a doubly linked list and -the next_run and prev_run fields keep all runnable threads on a -doubly linked list. Mutexes are stubs for FAKE_THREADS. Condition -variables are implemented as a list of waiting threads. - - -Mutexes and condition variables - -The API is via macros MUTEX_{INIT,LOCK,UNLOCK,DESTROY} and -COND_{INIT,WAIT,SIGNAL,BROADCAST,DESTROY}. - -A mutex is only required to be a simple, fast mutex (e.g. it does not -have to be recursive). It is only ever held across very short pieces -of code. Condition variables are only ever signalled/broadcast while -their associated mutex is held. (This constraint simplifies the -implementation of condition variables in certain porting situations.) -For POSIX threads, perl mutexes and condition variables correspond to -POSIX ones. For FAKE_THREADS, mutexes are stubs and condition variables -are implemented as lists of waiting threads. For FAKE_THREADS, a thread -waits on a condition variable by removing itself from the runnable -list, calling SCHEDULE to change thr to the next appropriate -runnable thread and returning op (i.e. the new threads next op). -This means that fake threads can only block while in PP code. -A PP function which contains a COND_WAIT must be prepared to -handle such restarts and can use the field "private" of struct -thread to record its state. For fake threads, COND_SIGNAL and -COND_BROADCAST work by putting back all the threads on the -condition variables list into the run queue. Note that a mutex -must *not* be held while returning from a PP function. - -Perl locks and condition variables are both implemented as a -condpair_t structure, containing a mutex, an "owner" condition -variable, an owner thread field and another condition variable). -The structure is attached by 'm' magic to any SV. pp_lock locks -such an object by waiting on the ownercond condition variable until -the owner field is zero and then setting the owner field to its own -thread pointer. The lock is semantically recursive so if the owner -field already matches the current thread then pp_lock returns -straight away. If the owner field has to be filled in then -unlock_condpair is queued as an end-of-block destructor and -that function zeroes out the owner field and signals the ownercond -condition variable, thus waking up any other thread that wants to -lock it. When used as a condition variable, the condpair is locked -(involving the above wait-for-ownership and setting the owner field) -and the spare condition variable field is used for waiting on. - - -Thread states - - - $t->join -R_JOINABLE ---------------------> R_JOINED >----\ - | \ pthread_join(t) | ^ | - | \ | | join | pthread_join - | \ | | | - | \ | \------/ - | \ | - | \ | - | $t->detach\ pthread_detach | - | _\| | -ends| R_DETACHED ends | unlink - | \ | - | ends \ unlink | - | \ | - | \ | - | \ | - | \ | - | \ | - V join detach _\| V -ZOMBIE ----------------------------> DEAD - pthread_join pthread_detach - and unlink and unlink - - +As of 5.9.0, the older threading model is not supported anymore. Malcolm Beattie mbeattie@sable.ox.ac.uk @@ -347,3 +21,6 @@ Gurusamy Sarathy More platforms added 26 Jul 1999 by Jarkko Hietaniemi + +Removed 5005threads support 03 Oct 2002 by +H.Merijn Brand |