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https://issues.apache.org/jira/browse/THRIFT-3932?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15533833#comment-15533833
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Buğra Gedik edited comment on THRIFT-3932 at 9/29/16 7:40 PM:
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You are right, that one addresses the same issue. I looked at the code from
here: https://github.com/apache/thrift/pull/992/files However, incrementing
{{workerCount_}} under one monitor ({{monitor_}}), and decrementing it under
another monitor ({{workerMonitor_}}) that does not share its mutex with the
first one seems odd to me.
was (Author: bgedik):
You are right, that one addresses the same issue. I looked at the code from
here: https://github.com/apache/thrift/pull/992/files However, incrementing
{{workerCount_}} under one monitor ({{manager_->monitor_}}), and decrementing
it under another monitor ({{manager_->workerMonitor_}}) that does not share its
mutex with the first one seems odd to me.
> C++ ThreadManager has a rare termination race
> ---------------------------------------------
>
> Key: THRIFT-3932
> URL: https://issues.apache.org/jira/browse/THRIFT-3932
> Project: Thrift
> Issue Type: Bug
> Components: C++ - Library
> Reporter: Buğra Gedik
> Assignee: James E. King, III
> Attachments: thrift-patch
>
>
> {{ThreadManger::join}} calls {{stopImpl(true)}}, which in turn calls
> {{removeWorker(workerCount_);}}. The latter waits until {{while (workerCount_
> != workerMaxCount_)}}. Within the {{run}} method of the workers, the last
> thread that detects {{workerCount_ == workerMaxCount_}} notifies
> {{removeWorker}}. The {{run}} method has the following additional code that
> is executed at the very end:
> {code}
> {
> Synchronized s(manager_->workerMonitor_);
> manager_->deadWorkers_.insert(this->thread());
> if (notifyManager) {
> manager_->workerMonitor_.notify();
> }
> }
> {code}
> This is an independent synchronized block. Now assume 2 threads. One of them
> has {{notifyManager=true}} as it detected the {{workerCount_ ==
> workerMaxCount_}} condition earlier. It is possible that this thread gets to
> execute the above code block first, {{ThreadManager}}'s {{removeWorker}}
> method unblocks, and eventually {{ThreadManager}}'s {{join}} returns and the
> object is destructed. When the other thread reaches the synchronized block
> above, it will crash, as the manager is not around anymore.
> Besides, {{ThreadManager}} never joins its threads.
> Attached is a patch.
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