Fix JULIA_EXCLUSIVE setting affinity on non-worker threads #57136
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With JULIA_EXCLUSIVE=1, we would try to give both worker and interactive threads an exclusive CPU, causing --threads=auto to produce a "Too many threads requested" error. Fixes JuliaLang#50702.
vtjnash
approved these changes
Jan 22, 2025
topolarity
reviewed
Jan 23, 2025
| @@ -794,6 +794,9 @@ void jl_start_threads(void) | |||
| { | |||
| int nthreads = jl_atomic_load_relaxed(&jl_n_threads); | |||
| int ngcthreads = jl_n_gcthreads; | |||
| int nthreadsi = jl_n_threads_per_pool[0]; | |||
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Is this ninteractive_threads? Might be worth the longer name for clarity, or a comment
| uv_thread_setaffinity(&uvtid, mask, NULL, cpumasksize); | ||
| mask[0] = 0; | ||
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| if (nthreadsi == 0) { |
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Can you leave a comment explaining the guard?
It seems to silently ignore the exclusive setting, which is worth a call-out (or maybe the affinity is configured elsewhere)
| for (i = 1; i < nmutator_threads; ++i) { | ||
| jl_threadarg_t *t = (jl_threadarg_t *)malloc_s(sizeof(jl_threadarg_t)); // ownership will be passed to the thread | ||
| t->tid = i; | ||
| t->barrier = &thread_init_done; | ||
| uv_thread_create(&uvtid, jl_threadfun, t); | ||
| if (exclusive) { | ||
| mask[i] = 1; | ||
| if (exclusive && i > nthreadsi) { |
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Suggested change
| if (exclusive && i > nthreadsi) { | |
| if (exclusive && i > nthreadsi) { | |
| // assign any non-interactive threads consecutively, starting at CPU1 | |
| assert(i - nthreadsi < cpumasksize); |
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With JULIA_EXCLUSIVE=1, we would try to give both worker and interactive threads an exclusive CPU, causing --threads=auto to produce a "Too many threads requested" error.
Fixes #50702.