Use atomics for the StickyWorkqueue array instead of a lock #55514
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vchuravy
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Aug 16, 2024
base/task.jl
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| while length(qs) < tid | ||
| nt = Threads.maxthreadid() | ||
| @assert tid <= nt | ||
| new_qs = copyto!(typeof(qs)(undef, length(qs) + nt - 1), qs) |
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Why is this length(as) + nt - 1 I see that this is the old code as well. Are we implementing doubling? Maybe worth a comment?
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This is a data race if you don't have a lock around the whole thing to make it valid
giordano
reviewed
Aug 16, 2024
vtjnash
reviewed
Aug 17, 2024
base/task.jl
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| end | ||
| if !isassigned(qs, tid) | ||
| @inbounds qs[tid] = StickyWorkqueue() |
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This also needs atomics now that it is no longer behind a lock
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Now that I think about it. This is probably unsafe, we need to eagerly allocate the queues now, because there's no way to make sure that qs is still the same as workqueues here.
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The change to Memory is probably still a net positive |
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The title of the PR is now very inaccurate though |
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I was implementing a way to change the number of workqueues in a lock-free way for use with my workstealing development and ported it to the one we already have in julia