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https://issues.apache.org/jira/browse/BEAM-9399?focusedWorklogId=482231&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-482231
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ASF GitHub Bot logged work on BEAM-9399:
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Author: ASF GitHub Bot
Created on: 11/Sep/20 18:52
Start Date: 11/Sep/20 18:52
Worklog Time Spent: 10m
Work Description: kennknowles commented on pull request #12825:
URL: https://github.com/apache/beam/pull/12825#issuecomment-691258077
I believe the trouble here is that it mixes all log levels on stderr, while
the log reporting in the UI reports all stderr lines at the same severity. I
cannot recall if they are all INFO or all WARN in the UI, but either way it is
incorrect and confusing. So we need the corresponding change to make sure that
doesn't happen. Just drive by comment because I've encountered this.
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Issue Time Tracking
-------------------
Worklog Id: (was: 482231)
Time Spent: 6.5h (was: 6h 20m)
> 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: 6.5h
> 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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