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v0.4.5

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@github-actions github-actions released this 26 Aug 02:53
· 3 commits to main since this release
v0.4.5
5dd7d21

RustyCSV 0.4.5 stops bundling a memory allocator by default, which fixes a VM-killing segfault when another NIF in the same BEAM also bundles one.

Fixed

  • Fixed a VM-killing segfault when another NIF in the same BEAM also bundles mimalloc. Two statically linked mimalloc copies share a fixed thread-local slot on macOS but keep private page maps, so one copy's realloc can be handed a block the other allocated, miss its page-map lookup, report a usable size of 0, and copy zero bytes — freeing the original and returning fresh, uninitialised memory. RustyCSV bundled mimalloc by default through 0.4.4 and was one half of the pair behind three beam.smp crashes on 2026-08-25; the reproduction was built against rusty_csv 0.4.4. The corruption is symmetric, so the damage lands in whichever library reallocates next, and no validation inside RustyCSV could have detected it — it happens in the allocator, below the library.

Changed

  • mimalloc is now an opt-in cargo feature rather than a default, so published artifacts bundle no allocator. Measured on an M1 Pro, the cost is about 22% across a mixed decode/encode workload and is concentrated in the multi-threaded paths: strategy: :parallel encoding is 1.5× slower and 64 KB-chunk streaming 1.34× slower, while single-threaded encoding is unchanged (within 1%) and single-threaded decoding is 3–8% slower (21% for headers: true). To opt back in, after checking RustyCSV is the only allocator-bundling NIF in your VM:

    RUSTYCSV_ALLOCATOR=mimalloc FORCE_RUSTYCSV_BUILD=1 mix compile

    See allocator safety.

Added

  • nif_version_2_18 cargo feature for OTP 29. Not yet wired into nif_versions — rustler_precompiled 0.9.0 caps supported versions at 2.17, so OTP 29 keeps loading the 2.17 artifact, which is verified to work correctly.
  • A regression test that fails the build if a default artifact ever links a bundled allocator again.

Documentation

  • Added allocator safety: the hazard, how to audit the other NIFs in your VM, the measured performance tradeoff, and what does not fix it.
  • Corrected the README and architecture notes, which described mimalloc as the default allocator.

See the full changelog for details.

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