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author | Nadeem Vawda <nadeem.vawda@gmail.com> | 2012-01-02 02:24:20 +0200 |
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committer | Nadeem Vawda <nadeem.vawda@gmail.com> | 2012-01-02 02:24:20 +0200 |
commit | be4f13208842c821eb7fd97d036989dfdd4879d7 (patch) | |
tree | c8282913c9ff1098c3b73d99542732212e9ea8b0 /Doc/library/lzma.rst | |
parent | 8fefd244745d0b6c69707ab134320048878e68ba (diff) | |
download | cpython-be4f13208842c821eb7fd97d036989dfdd4879d7.tar.gz |
Add note on memory usage to LZMACompressor doc.
Diffstat (limited to 'Doc/library/lzma.rst')
-rw-r--r-- | Doc/library/lzma.rst | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/Doc/library/lzma.rst b/Doc/library/lzma.rst index 4e6db15a74..3941ec18d0 100644 --- a/Doc/library/lzma.rst +++ b/Doc/library/lzma.rst @@ -120,8 +120,16 @@ Compressing and decompressing data in memory ``9`` (inclusive), optionally OR-ed with the constant :const:`PRESET_EXTREME`. If neither *preset* nor *filters* are given, the default behavior is to use :const:`PRESET_DEFAULT` (preset level ``6``). - Higher presets produce smaller output, but make compression more CPU- and - memory-intensive, and also increase the memory required for decompression. + Higher presets produce smaller output, but make the compression process + slower. + + .. note:: + + In addition to being more CPU-intensive, compression with higher presets + also requires much more memory (and produces output that needs more memory + to decompress). With preset ``9`` for example, the overhead for an + :class:`LZMACompressor` object can be as high as 800MiB. For this reason, + it is generally best to stick with the default preset. The *filters* argument (if provided) should be a filter chain specifier. See :ref:`filter-chain-specs` for details. |