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Fix performance regression in unzip of local wheels#19636

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Fix performance regression in unzip of local wheels#19636
zanieb wants to merge 1 commit into
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zb/sync-clone

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@zanieb

@zanieb zanieb commented Jun 1, 2026 •
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Closes #19635

I reproduced the issue over increasing target sizes

File count Directory count 0.11.14 0.11.15 Regression
1,000 250 0.045s 0.048s 1.1x
3,000 750 0.117s 0.147s 1.3x
10,000 2,500 0.379s 0.844s 2.2x
30,000 7,500 1.16s 11.42s 9.8x
100,000 25,000 3.59s 213.5s 59.5x

The issue appears to not be build, e.g., uv build --wheel was no affected, but unpacking the wheel into the cache.

The root cause is that cloning the zip reader is really expensive in rs-async-zip, unlike the sync zip crate.

Here are the results for 100k files, including after this fix.

Binary Prepare Install Total User CPU Sys CPU
0.11.14 3.71s 28.59s 38.41s 3.17s 42.04s
0.11.15 3m34s 30.84s 251.03s 1755.53s 1367.60s
branch 3.07s 27.03s 35.09s 3.57s 39.95s

@zanieb

zanieb commented Jun 1, 2026

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The proper solution, imo, is astral-sh/rs-async-zip#41

@zanieb zanieb mentioned this pull request Jun 1, 2026
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@zanieb
Use Arc for ZipFile in ZipFileReader so cloning is not expensive (
8fb82f3 
#41)

See astral-sh/uv#19636

This matches the sync `zip` crate


https://github.com/zip-rs/zip2/blob/0f2dd44ffa016c90490a90c5580ef428fb42e9c5/src/read/zip_archive.rs#L85-L89
@zanieb zanieb closed this Jun 1, 2026
@woodruffw woodruffw mentioned this pull request Jun 1, 2026
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@woodruffw
Fix performance regression in unzip of local wheels (#19637)
5ba95e0 
## Summary

Closes #19636. Fixes #19635.

## Test Plan

NFC.

Signed-off-by: William Woodruff <william@yossarian.net>
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Significant performance degradation building packages

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