Allocate thread IDs for wasi_thread_spawn sequentially#7884
Merged
abrown merged 1 commit intobytecodealliance:mainfrom Feb 12, 2024
Merged
Allocate thread IDs for wasi_thread_spawn sequentially#7884abrown merged 1 commit intobytecodealliance:mainfrom
abrown merged 1 commit intobytecodealliance:mainfrom
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abrown
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Feb 12, 2024
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@Milek7, thanks for the PR! |
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TID returned by
wasi_thread_spawnmust be non-zero and upper three bits must always be zero: https://github.com/WebAssembly/wasi-threads?tab=readme-ov-file#design-choice-thread-idsCurrent implementation didn't fulfill this requirements, only clearing the top bit from random value. This breaks wasi-libc mutexes when random TID is larger or equal to 0x3FFFFFFF.
Additionally, from birthday paradox probability of collision in allowed TID range nears 50% after spawning 27000 threads. This is large but not totally impossible, thus replace random generation with sequential allocation.