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https://issues.apache.org/jira/browse/OOZIE-3646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17490084#comment-17490084
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Andras Salamon commented on OOZIE-3646:
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Great finding [~zuston] and thanks for the patch.
I checked the unit test locally. It was failing without the fix and it passes
with the fix which is very good.
The code looks to me. The {{synchronized (SignalXCommand.class)}} looks a bit
dangerous to me, but I have no better idea.
+1
> Possible dead-lock in SignalXCommand
> ------------------------------------
>
> Key: OOZIE-3646
> URL: https://issues.apache.org/jira/browse/OOZIE-3646
> Project: Oozie
> Issue Type: Bug
> Reporter: Junfan Zhang
> Assignee: Junfan Zhang
> Priority: Major
> Attachments: OOZIE-3646-002.patch, OOZIE-3646-003.patch,
> OOZIE-3646.patch-1, OOZIE-3646.patch-2, a1.png
>
>
> The limited thread execution mechanism aims to solve the dead-lock when all
> active threads are executing the SignalXCommand's invokeAll method.
> h2. Dead-lock when to happen
> Assuming that Oozie CallableQueue thread pool size is 120, when all threads
> are executing the {{SignalXCommand.startForkedActions}} method, a deadlock
> occurs.
> Because in {{SignalXCommand.startForkedActions}}, the code of
> {code:java}
> List<Future<ActionExecutorContext>> futures =
> Services.get().get(CallableQueueService.class)
> .invokeAll(tasks);
> {code}
> will be sync executed, however now all callableQueue threads are busy.
> h2. Solution
> 1. Need to limit directly invokeAll call when the num of rest threads is less
> than the tasks
> 2. To obtain correct active threads number in callableQueue, the
> SignalXCommand.class lock is needed.
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