Repository navigation
gh-160535: Keep the ZstdDict alive until the zstd context is freed - #160536
Merged
Merged
Conversation
The garbage collector could release a ZstdCompressor's dictionary, or the digested dictionaries cached by the ZstdDict, while worker threads of the compression context were still reading them. They are now only released on deallocation, after the context has been freed. ANT-2026-CT3P1CSJ
gpshead
added
needs backport to 3.14
|
Thanks @gpshead for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15. |
|
GH-160635 is a backport of this pull request to the 3.15 branch. |
|
GH-160636 is a backport of this pull request to the 3.14 branch. |
gpshead
added a commit
that referenced
this pull request
Oct 25, 2026
…reed (GH-160536) (#160636) gh-160535: Keep the ZstdDict alive until the zstd context is freed (GH-160536) The garbage collector could release a ZstdCompressor's dictionary, or the digested dictionaries cached by the ZstdDict, while worker threads of the compression context were still reading them. They are now only released on deallocation, after the context has been freed. ANT-2026-CT3P1CSJ + Visit the type in the compressor and decompressor traverse; move NEWS to Library (cherry picked from commit b949033) Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
gpshead
added a commit
that referenced
this pull request
Oct 25, 2026
…reed (GH-160536) (#160635) gh-160535: Keep the ZstdDict alive until the zstd context is freed (GH-160536) The garbage collector could release a ZstdCompressor's dictionary, or the digested dictionaries cached by the ZstdDict, while worker threads of the compression context were still reading them. They are now only released on deallocation, after the context has been freed. ANT-2026-CT3P1CSJ + Visit the type in the compressor and decompressor traverse; move NEWS to Library (cherry picked from commit b949033) Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
ZstdCompressorandZstdDecompressorno longer have atp_clear, andZstdDictno longer exposes its cache of digested dictionaries to the garbage collector, so the dictionary and itsZSTD_CDictinstances are only released in the deallocators, afterZSTD_freeCCtx()/ZSTD_freeDCtx()has stopped the worker threads. None of these objects can close a reference cycle on its own (the only route back is through a mutable object reachable from thezstd_dicttuple, which has its owntp_clear), sotp_traversealone is enough. The decompressor has no worker threads and is changed only to keep the same ordering rule in both types. The new test runs in a subprocess because detecting the freed read depends on the allocator; it fails on Linux/glibc without the fix and may pass vacuously elsewhere.Fixes #160535
ANT-2026-CT3P1CSJ
ZstdCompressortogether with itsZstdDict#160535