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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
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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