fix freeze on @threads loop exit
#45899
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This was referenced Jul 5, 2022
tkf
approved these changes
Jul 6, 2022
Closes #45626, hopefully.
DilumAluthge
removed
the
merge me
ffucci
pushed a commit
to ffucci/julia
that referenced
this pull request
Aug 11, 2022
Closes JuliaLang#45626, hopefully.
pcjentsch
pushed a commit
to pcjentsch/julia
that referenced
this pull request
Aug 18, 2022
Closes JuliaLang#45626, hopefully.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Closes #45626, hopefully. I don't have the hardware available to reproduce this, but I think this fence was missing.
It also perhaps might be considered a defect in libuv, since it explicitly does a "cheap read" here:
https://github.com/libuv/libuv/blob/master/src/unix/async.c#L65
https://github.com/libuv/libuv/blob/master/src/win/async.c#L58
But that might not agree with the doc's claim that "If uv_async_send() is called again after the callback was called, it will be called again", if we think that means there should exist an implied happens-before edge. But the wording is imprecise as to how it defines "after the callback" on the other thread. The fast-read optimization is never required to observe the other thread's behavior, so it is never required to call the callback again, unless the user of libuv inserts their own synchronization fences that enforce progress.
http://docs.libuv.org/en/v1.x/async.html#c.uv_async_send