Regularly wake from timely to deal with eaten wake-ups#13972
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Regularly wake from timely to deal with eaten wake-ups#13972frankmcsherry wants to merge 1 commit into
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benesch
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This is an alternative to MaterializeInc#13972 that avoids hardcoding the 1s timeout. As described there: This addresses a race that appears in storaged where the LocalClient will wake worker threads that have inbound messages to read, but the wake-ups are (or appear to be) eaten by various non-Timely sleepy moments in the code. If these wake-ups are quietly eaten, and then Timely is entered with a None timeout and nothing to do, it will sleep forever. Would close MaterializeInc#13972 if merged.
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benesch
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Jul 30, 2022
This is an alternative to MaterializeInc#13972 that avoids hardcoding the 1s timeout. As described there: This addresses a race that appears in storaged where the LocalClient will wake worker threads that have inbound messages to read, but the wake-ups are (or appear to be) eaten by various non-Timely sleepy moments in the code. If these wake-ups are quietly eaten, and then Timely is entered with a None timeout and nothing to do, it will sleep forever. Would close MaterializeInc#13972 if merged. Many, many thanks to @frankmcsherry for determining that lost wakeups were the cause of this issue. Co-authored-by: Frank McSherry <fmcsherry@me.com>
benesch
added a commit
that referenced
this pull request
Jul 31, 2022
This is an alternative to #13972 that avoids hardcoding the 1s timeout. As described there: This addresses a race that appears in storaged where the LocalClient will wake worker threads that have inbound messages to read, but the wake-ups are (or appear to be) eaten by various non-Timely sleepy moments in the code. If these wake-ups are quietly eaten, and then Timely is entered with a None timeout and nothing to do, it will sleep forever. Would close #13972 if merged. Many, many thanks to @frankmcsherry for determining that lost wakeups were the cause of this issue. Co-authored-by: Frank McSherry <fmcsherry@me.com>
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This addresses a race that appears in
storagedwhere theLocalClientwill wake worker threads that have inbound messages to read, but the wake-ups are (or appear to be) eaten by various non-Timely sleepy moments in the code. If these wake-ups are quietly eaten, and then Timely is entered with aNonetimeout and nothing to do, it will sleep forever.It would be nice to fix this better, but just introducing a time-out seems to be the most robust way to fix this.
Motivation
CI had various timeouts that were experienced when
storagedclients were "slow-rolled" commands, being provided first withInitializationCompletecommands and then source creation commands. The creation commands could be missed, when presented in this order, as was introduced in 9b2eb6d. This has been reverted, but if it is reintroduced with this change the timeout does not appear to manifest.Tips for reviewer
Checklist
This PR has adequate test coverage / QA involvement has been duly considered.
This PR evolves an existing
$T ⇔ Proto$Tmapping (possibly in a backwards-incompatible way) and therefore is tagged with aT-protobuflabel.This PR includes the following user-facing behavior changes: