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Date: Fri, 2 Sep 2016 16:19:20 +0000 (UTC)
From: "Manoj Govindassamy (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.13002195.1472771492000.480306.1472833160931@Atlassian.JIRA>
In-Reply-To: <JIRA.13002195.1472771492000@Atlassian.JIRA>
References: <JIRA.13002195.1472771492000@Atlassian.JIRA> <JIRA.13002195.1472771492451@arcas>
Subject: [jira] [Commented] (HDFS-10830) FsDatasetImpl#removeVolumes()
 crashes with IllegalMonitorStateException when vol being removed is in use
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archived-at: Fri, 02 Sep 2016 16:19:28 -0000


    [ https://issues.apache.org/jira/browse/HDFS-10830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15458948#comment-15458948 ] 

Manoj Govindassamy commented on HDFS-10830:
-------------------------------------------

Thanks for working on this [~arpitagarwal] and submitting a patch. Would you be willing to own this bug ? If so, please feel free to assign this bug to yourself. 

Had a quick look at the patch. I believe the submitted patch will not throw IllegalMonitorStateException. But, looks like the patch also  retains the old "polling" model. That is, wait and check in a loop. Wouldn't it be better to go for the following ..
* wait and signal model compared to polling
* and with a overall timeout to give up or abort the remove volume operation as the other concurrent user is taking a long time to finish his operations and the reference count not going to zero.

Please let me know your thoughts on above.

> FsDatasetImpl#removeVolumes() crashes with IllegalMonitorStateException when vol being removed is in use
> --------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-10830
>                 URL: https://issues.apache.org/jira/browse/HDFS-10830
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: hdfs
>    Affects Versions: 3.0.0-alpha1
>            Reporter: Manoj Govindassamy
>            Assignee: Manoj Govindassamy
>         Attachments: HDFS-10830.01.patch
>
>
> {{FsDatasetImpl#removeVolumes()}} operation crashes abruptly with IllegalMonitorStateException whenever the volume being removed is in use concurrently.
> Looks like {{removeVolumes()}} is waiting on a monitor object "this" (that is FsDatasetImpl) which it has never locked, leading to  IllegalMonitorStateException. This monitor wait happens only the volume being removed is in use (referencecount > 0). The thread performing this remove volume operation thus crashes abruptly and block invalidations for the remove volumes are totally skipped. 
> {code:title=FsDatasetImpl.java|borderStyle=solid}
> @Override
> public void removeVolumes(Set<File> volumesToRemove, boolean clearFailure) {
> ..
> ..
> try (AutoCloseableLock lock = datasetLock.acquire()) {   <== LOCK acquire datasetLock
> for (int idx = 0; idx < dataStorage.getNumStorageDirs(); idx++) {
>   .. .. ..
>   asyncDiskService.removeVolume(sd.getCurrentDir());     <== volume SD1 remove
>   volumes.removeVolume(absRoot, clearFailure);
>   volumes.waitVolumeRemoved(5000, this);                 <== WAIT on "this" ?? But, we haven't locked it yet.
>                                                              This will cause IllegalMonitorStateException
>                                                              and crash getBlockReports()/FBR thread!
>   for (String bpid : volumeMap.getBlockPoolList()) {
>     List<ReplicaInfo> blocks = new ArrayList<>();
>     for (Iterator<ReplicaInfo> it = volumeMap.replicas(bpid).iterator();
>          it.hasNext(); ) {
>         .. .. .. 
>         it.remove();                                     <== volumeMap removal
>       }
>     blkToInvalidate.put(bpid, blocks);
>   }
>  .. ..
> }                                                        <== LOCK release datasetLock   
> // Call this outside the lock.
> for (Map.Entry<String, List<ReplicaInfo>> entry :
> blkToInvalidate.entrySet()) {
>  ..
>  for (ReplicaInfo block : blocks) {
>   invalidate(bpid, block);                               <== Notify NN of Block removal
>  }
> }
> {code}


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