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https://issues.apache.org/jira/browse/BEAM-9399?focusedWorklogId=483825&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-483825
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ASF GitHub Bot logged work on BEAM-9399:
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Author: ASF GitHub Bot
Created on: 14/Sep/20 07:16
Start Date: 14/Sep/20 07:16
Worklog Time Spent: 10m
Work Description: scwhittle commented on pull request #12825:
URL: https://github.com/apache/beam/pull/12825#issuecomment-691867771
I am only changing how errors from within the DataflowWorkerLoggingHandler
itself are reported, for example an error publishing to stackdriver. I agree
that logging to stderr is difficult to view in the UI, but that seems separate
from the deadlock we originally fixed (the Jira has more details) and the
erroneous precondition introduced when that was added. Kenn, does the limited
scope of this change address your concerns? I am not changing it to use the
original System.err generally
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Issue Time Tracking
-------------------
Worklog Id: (was: 483825)
Time Spent: 7h 50m (was: 7h 40m)
> Possible deadlock between DataflowWorkerLoggingHandler and overridden
> System.err PrintStream
> --------------------------------------------------------------------------------------------
>
> Key: BEAM-9399
> URL: https://issues.apache.org/jira/browse/BEAM-9399
> Project: Beam
> Issue Type: Bug
> Components: runner-dataflow
> Reporter: Sam Whittle
> Assignee: Sam Whittle
> Priority: P3
> Fix For: 2.21.0
>
> Time Spent: 7h 50m
> Remaining Estimate: 0h
>
> When an exception is encountered in DataflowWorkerLoggingHandler the
> ErrorManager is used to log the exception. ErrorManager uses System.err
> which is overridden to be a PrintStream that writes back into
> DataflowWorkerLoggingHandler.
> This has the lock ordering DataflowWorkerLoggingHandler -> PrintStream.
> Other logging of System.err has the inverse lock ordering
> PrintStream->DataflowWorkerLoggingHandler so there is potential for deadlock.
> This is one known cause of the inversion, but any other System.err logs from
> inside DataflowWorkerLoggingHandler could cause the same issue.
> Proposed fix is to address low-hanging fruit of having ErrorManager output to
> the original System.err. A full fix would be to improve our override of
> System.err to a PrintStream that can detect the locking inversion or possibly
> we could use the PrintStream mutex in both cases.
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