Scheduler: Use a "scheduler" task for thread sleep #57544
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vtjnash
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vtjnash
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This is currently blocked on what seems to be a bug in |
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…simage (#57656) This is quite tricky to test unfortunately, but #57544 caught this and this fixes that --------- Co-authored-by: Jameson Nash <[email protected]>
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…simage (#57656) This is quite tricky to test unfortunately, but #57544 caught this and this fixes that --------- Co-authored-by: Jameson Nash <[email protected]> (cherry picked from commit bf01638)
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Unblocked... thanks @gbaraldi! Now, some |
vtjnash
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Is there any chance of getting this backported to 1.12? It's quite tricky to debug and would be nice if it was fixed in the next release. |
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This small group of tests is written with assumptions about when and how the libuv event loop is run. As this PR changes this behavior, the tests needed adjusting.
Previously, this test depended on scheduler behavior, which is slightly changed in this PR. Changed the test to connect to a non-routable IP address so that it no longer depends on task ordering.
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Thanks @vtjnash for the idea on how to fix the Sockets test. |
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The |
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A Julia thread runs Julia's scheduler in the context of the switching task. If no task is found to switch to, the thread will sleep while holding onto the (possibly completed) task, preventing the task from being garbage collected. This recent Discourse post illustrates precisely this problem.
A solution to this would be for an idle Julia thread to switch to a "scheduler" task, thereby freeing the old task.
This PR uses
OncePerThreadto create a "scheduler" task (that does nothing but runwait()in a loop) and switches to that task when the thread finds itself idle.Other approaches considered and discarded in favor of this one: #57465 and #57543.