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Replace Base.Workqueues with a OncePerThread #58941

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@xal-0 xal-0 commented Jul 8, 2025

Simplify workqueue_for. While not strictly necessary, the acquire load in getindex(once::OncePerThread{T,F}, tid::Integer) makes ThreadSanitizer happy. With the existing implementation, we get false positives whenever a thread other than the one that originally allocated the array reads it:

==================
WARNING: ThreadSanitizer: data race (pid=6819)
  Atomic read of size 8 at 0xffff86bec058 by main thread:
    #0 getproperty Base_compiler.jl:57 (sys.so+0x113b478)
    #1 julia_pushNOT._1925 task.jl:868 (sys.so+0x113b478)
    #2 julia_enq_work_1896 task.jl:969 (sys.so+0x5cd218)
    #3 schedule task.jl:983 (sys.so+0x892294)
    #4 macro expansion threadingconstructs.jl:522 (sys.so+0x892294)
    #5 julia_start_profile_listener_60681 Base.jl:355 (sys.so+0x892294)
    #6 julia___init___60641 Base.jl:392 (sys.so+0x1178dc)
    #7 jfptr___init___60642 <null> (sys.so+0x118134)
    #8 _jl_invoke /home/user/c/julia/src/gf.c (libjulia-internal.so.1.13+0x5e9a4)
    #9 ijl_apply_generic /home/user/c/julia/src/gf.c:3892:12 (libjulia-internal.so.1.13+0x5e9a4)
    #10 jl_apply /home/user/c/julia/src/julia.h:2343:12 (libjulia-internal.so.1.13+0xbba74)
    #11 jl_module_run_initializer /home/user/c/julia/src/toplevel.c:68:13 (libjulia-internal.so.1.13+0xbba74)
    #12 _finish_jl_init_ /home/user/c/julia/src/init.c:632:13 (libjulia-internal.so.1.13+0x9c0fc)
    #13 ijl_init_ /home/user/c/julia/src/init.c:783:5 (libjulia-internal.so.1.13+0x9bcf4)
    #14 jl_repl_entrypoint /home/user/c/julia/src/jlapi.c:1125:5 (libjulia-internal.so.1.13+0xf7ec8)
    #15 jl_load_repl /home/user/c/julia/cli/loader_lib.c:601:12 (libjulia.so.1.13+0x11934)
    #16 main /home/user/c/julia/cli/loader_exe.c:58:15 (julia+0x10dc20)

  Previous write of size 8 at 0xffff86bec058 by thread T2:
    #0 IntrusiveLinkedListSynchronized task.jl:863 (sys.so+0x78d220)
    #1 macro expansion task.jl:932 (sys.so+0x78d220)
    #2 macro expansion lock.jl:376 (sys.so+0x78d220)
    #3 julia_workqueue_for_1933 task.jl:924 (sys.so+0x78d220)
    #4 julia_wait_2048 task.jl:1204 (sys.so+0x6255ac)
    #5 julia_task_done_hook_49205 task.jl:839 (sys.so+0x128fdc0)
    #6 jfptr_task_done_hook_49206 <null> (sys.so+0x902218)
    #7 _jl_invoke /home/user/c/julia/src/gf.c (libjulia-internal.so.1.13+0x5e9a4)
    #8 ijl_apply_generic /home/user/c/julia/src/gf.c:3892:12 (libjulia-internal.so.1.13+0x5e9a4)
    #9 jl_apply /home/user/c/julia/src/julia.h:2343:12 (libjulia-internal.so.1.13+0x9c79c)
    #10 jl_finish_task /home/user/c/julia/src/task.c:345:13 (libjulia-internal.so.1.13+0x9c79c)
    #11 jl_threadfun /home/user/c/julia/src/scheduler.c:122:5 (libjulia-internal.so.1.13+0xe7db8)

  Thread T2 (tid=6824, running) created by main thread at:
    #0 pthread_create <null> (julia+0x85f88)
    #1 uv_thread_create_ex /workspace/srcdir/libuv/src/unix/thread.c:172 (libjulia-internal.so.1.13+0x1a8d70)
    #2 _finish_jl_init_ /home/user/c/julia/src/init.c:618:5 (libjulia-internal.so.1.13+0x9c010)
    #3 ijl_init_ /home/user/c/julia/src/init.c:783:5 (libjulia-internal.so.1.13+0x9bcf4)
    #4 jl_repl_entrypoint /home/user/c/julia/src/jlapi.c:1125:5 (libjulia-internal.so.1.13+0xf7ec8)
    #5 jl_load_repl /home/user/c/julia/cli/loader_lib.c:601:12 (libjulia.so.1.13+0x11934)
    #6 main /home/user/c/julia/cli/loader_exe.c:58:15 (julia+0x10dc20)

SUMMARY: ThreadSanitizer: data race Base_compiler.jl:57 in getproperty
==================

@xal-0 xal-0 added the multithreading Base.Threads and related functionality label Jul 8, 2025
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