[jira] [Updated] (YARN-2945) FSLeafQueue#assignContainer - document the reason for using both write and read locks

["Karthik Kambatla (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/YARN-2945?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Karthik Kambatla updated YARN-2945:
-----------------------------------
    Summary: FSLeafQueue#assignContainer - document the reason for using both write and read locks  (was: FSLeafQueue should hold lock before and after sorting runnableApps in assignContainer)

> FSLeafQueue#assignContainer - document the reason for using both write and read locks
> -------------------------------------------------------------------------------------
>
>                 Key: YARN-2945
>                 URL: https://issues.apache.org/jira/browse/YARN-2945
>             Project: Hadoop YARN
>          Issue Type: Bug
>            Reporter: Tsuyoshi OZAWA
>            Assignee: Tsuyoshi OZAWA
>         Attachments: YARN-2945.001.patch, YARN-2945.002.patch
>
>
> After YARN-2910, assignContainer hold WriteLock while sorting and ReadLock while referencing runnableApps. This can cause interrupted assignment of containers regardless of the policy.
> {code}
>     writeLock.lock();
>     try {
>       Collections.sort(runnableApps, comparator);
>     } finally {
>       writeLock.unlock();
>     }
>     readLock.lock();
>     try {
>       for (FSAppAttempt sched : runnableApps) {
>         if (SchedulerAppUtils.isBlacklisted(sched, node, LOG)) {
>           continue;
>         }
>         assigned = sched.assignContainer(node);
>         if (!assigned.equals(Resources.none())) {
>           break;
>         }
>        }
>     } finally {
>       readLock.unlock();
>     }
> {code}



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