Avoid unnecessary array allocations in ZipArchive#123836
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stephentoub merged 1 commit intodotnet:mainfrom Feb 3, 2026
Merged
Avoid unnecessary array allocations in ZipArchive#123836stephentoub merged 1 commit intodotnet:mainfrom
stephentoub merged 1 commit intodotnet:mainfrom
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…y{Async}
And simplify a few open-coded loops into span operations.
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Tagging subscribers to this area: @karelz, @dotnet/area-system-io-compression |
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Pull request overview
Reduce GC pressure and simplify inner-loop code paths in System.IO.Compression by reusing buffers from ArrayPool<byte> and replacing manual loops with span operations.
Changes:
- Replace allocating range operations / intermediate arrays with pooled buffers when reading the Zip central directory (sync + async).
- Fix an allocation-heavy path in
ZipCentralDirectoryFileHeader.TryReadBlockAsyncby collating into a pooledMemory<byte>rather than creating a new array. - Simplify repeated writes in
InflaterManaged.DecodeDynamicBlockHeaderusingSpan.Fill/Span.Clear.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.Async.cs | Uses a pooled buffer to collate dynamic header data without extra array allocations. |
| src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchive.cs | Central directory read buffer is rented from ArrayPool<byte> instead of allocating a new array per read. |
| src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchive.Async.cs | Async central directory parsing avoids range-operator array allocations by using ReadOnlyMemory<byte> slices over pooled buffers. |
| src/libraries/System.IO.Compression/src/System/IO/Compression/DeflateManaged/InflaterManaged.cs | Replaces small write loops with span-based fill/clear operations. |
This was referenced Jan 31, 2026
alinpahontu2912
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Feb 3, 2026
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alinpahontu2912
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Lgtm, nice improvements
lewing
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to lewing/runtime
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Feb 9, 2026
And simplify a few open-coded loops into span operations.
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And simplify a few open-coded loops into span operations.