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Use at most 8 threads for the xz stream #98
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At preset 6, xz2 uses about 173MB of memory per thread. This adds up
quickly -- e.g. over 8GB of memory on a 48-CPU machine. If you happen to
try this in a 32-bit build, you'll get `LZMA_MEM_ERROR`.
We can limit this to a heuristic maximum number of threads to avoid
using so much memory, like xz's [`04_compress_easy_mt` example].
// The number 8 is arbitrarily chosen and may be too low or
// high depending on the compression preset and the computer
// being used.
[`04_compress_easy_mt` example]: https://github.com/xz-mirror/xz/blob/de1f47b2b40e960b7bc3acba754f66dd19705921/doc/examples/04_compress_easy_mt.c#L71
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This is not hypothetical -- I hit this error in a Fedora i686 build. The build machine had 2 socket Xeon E5-2670v3 (48 CPUs) with 128GB memory, but of course a 32-bit build has more limited address space. It ended with: |
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Oh wow, now that's gnarly! |
Centril
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Aug 29, 2019
…Simulacrum Update rust-installer to limit memory use See rust-lang/rust-installer#98 -- on a many-core machine, the xz memory for so many threads is more than a 32-bit process can handle. The xz stream is now limited to 8 threads. r? @alexcrichton
Centril
added a commit
to Centril/rust
that referenced
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Aug 29, 2019
…Simulacrum Update rust-installer to limit memory use See rust-lang/rust-installer#98 -- on a many-core machine, the xz memory for so many threads is more than a 32-bit process can handle. The xz stream is now limited to 8 threads. r? @alexcrichton
Centril
added a commit
to Centril/rust
that referenced
this pull request
Aug 29, 2019
…Simulacrum Update rust-installer to limit memory use See rust-lang/rust-installer#98 -- on a many-core machine, the xz memory for so many threads is more than a 32-bit process can handle. The xz stream is now limited to 8 threads. r? @alexcrichton
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At preset 6, xz2 uses about 173MB of memory per thread. This adds up
quickly -- e.g. over 8GB of memory on a 48-CPU machine. If you happen to
try this in a 32-bit build, you'll get
LZMA_MEM_ERROR.We can limit this to a heuristic maximum number of threads to avoid
using so much memory, like xz's
04_compress_easy_mtexample.