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From "Allen Wittenauer (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-7314) Aborted DFSClient's impact on long running service like YARN
Date Wed, 06 May 2015 03:26:47 GMT

     [ https://issues.apache.org/jira/browse/HDFS-7314?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Allen Wittenauer updated HDFS-7314:
-----------------------------------
    Labels: BB2015-05-TBR  (was: )

> Aborted DFSClient's impact on long running service like YARN
> ------------------------------------------------------------
>
>                 Key: HDFS-7314
>                 URL: https://issues.apache.org/jira/browse/HDFS-7314
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Ming Ma
>            Assignee: Ming Ma
>              Labels: BB2015-05-TBR
>         Attachments: HDFS-7314-2.patch, HDFS-7314-3.patch, HDFS-7314-4.patch, HDFS-7314-5.patch,
HDFS-7314-6.patch, HDFS-7314-7.patch, HDFS-7314.patch
>
>
> It happened in YARN nodemanger scenario. But it could happen to any long running service
that use cached instance of DistrbutedFileSystem.
> 1. Active NN is under heavy load. So it became unavailable for 10 minutes; any DFSClient
request will get ConnectTimeoutException.
> 2. YARN nodemanager use DFSClient for certain write operation such as log aggregator
or shared cache in YARN-1492. DFSClient used by YARN NM's renewLease RPC got ConnectTimeoutException.
> {noformat}
> 2014-10-29 01:36:19,559 WARN org.apache.hadoop.hdfs.LeaseRenewer: Failed to renew lease
for [DFSClient_NONMAPREDUCE_-550838118_1] for 372 seconds.  Aborting ...
> {noformat}
> 3. After DFSClient is in Aborted state, YARN NM can't use that cached instance of DistributedFileSystem.
> {noformat}
> 2014-10-29 20:26:23,991 INFO org.apache.hadoop.yarn.server.nodemanager.containermanager.localizer.ResourceLocalizationService:
Failed to download rsrc...
> java.io.IOException: Filesystem closed
>         at org.apache.hadoop.hdfs.DFSClient.checkOpen(DFSClient.java:727)
>         at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:1780)
>         at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1124)
>         at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1120)
>         at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
>         at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1120)
>         at org.apache.hadoop.yarn.util.FSDownload.copy(FSDownload.java:237)
>         at org.apache.hadoop.yarn.util.FSDownload.call(FSDownload.java:340)
>         at org.apache.hadoop.yarn.util.FSDownload.call(FSDownload.java:57)
>         at java.util.concurrent.FutureTask.run(FutureTask.java:262)
>         at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
>         at java.util.concurrent.FutureTask.run(FutureTask.java:262)
>         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
>         at java.lang.Thread.run(Thread.java:745)
> {noformat}
> We can make YARN or DFSClient more tolerant to temporary NN unavailability. Given the
callstack is YARN -> DistributedFileSystem -> DFSClient, this can be addressed at different
layers.
> * YARN closes the DistributedFileSystem object when it receives some well defined exception.
Then the next HDFS call will create a new instance of DistributedFileSystem. We have to fix
all the places in YARN. Plus other HDFS applications need to address this as well.
> * DistributedFileSystem detects Aborted DFSClient and create a new instance of DFSClient.
We will need to fix all the places DistributedFileSystem calls DFSClient.
> * After DFSClient gets into Aborted state, it doesn't have to reject all requests , instead
it can retry. If NN is available again it can transition to healthy state.
> Comments?



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