Stream the parallel xz/gz tarball generation #76
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This melds the serial-`Tee` and parallel-batched approaches from before and after commit adea17e. Now we can get the same multithreaded speedup without having to build the entire uncompressed tarball in memory first. The new `impl Write for RayonTee` uses `rayon::join` to split the compression work for each buffer to separate threads. This is scoped, so it can be fully zero-copy, sharing the input buffer directly. This is all wrapped in a 1 MiB `BufWriter` to balance the cost of thread wake-ups and synchronization. The net performance is unchanged, using around 125% CPU -- approximately 4:1 time spent in xz versus gz. The overall memory use is much reduced, now independent of the tarball size -- just a few MiB on top of the fixed-cost 674 MiB compressor memory requirements of `xz -9`.
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Awesome, thanks @cuviper! |
cuviper
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Pull in rust-lang/rust-installer#76 to get streamed tarball generation, rather than batching it all in memory, while still getting the benefit of compressing in parallel.
kennytm
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…k-Simulacrum Update rust-installer for streaming parallelism Pull in rust-lang/rust-installer#76 to get streamed tarball generation, rather than batching it all in memory, while still getting the benefit of compressing in parallel.
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This melds the serial-
Teeand parallel-batched approaches from beforeand after commit adea17e. Now we can get the same multithreaded speedup
without having to build the entire uncompressed tarball in memory first.
The new
impl Write for RayonTeeusesrayon::jointo split thecompression work for each buffer to separate threads. This is scoped,
so it can be fully zero-copy, sharing the input buffer directly. This
is all wrapped in a 1 MiB
BufWriterto balance the cost of threadwake-ups and synchronization.
The net performance is unchanged, using around 125% CPU -- approximately
4:1 time spent in xz versus gz. The overall memory use is much reduced,
now independent of the tarball size -- just a few MiB on top of the
fixed-cost 674 MiB compressor memory requirements of
xz -9.Fixes #75.