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Date: Wed, 27 May 2015 03:27:17 +0000 (UTC)
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Message-ID: <JIRA.12830986.1432034768000.34894.1432697237470@Atlassian.JIRA>
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Subject: [jira] [Commented] (HDFS-8429) The DomainSocketWatcher thread
 should not block other threads if it dies
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    [ https://issues.apache.org/jira/browse/HDFS-8429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14560341#comment-14560341 ] 

Hadoop QA commented on HDFS-8429:
---------------------------------

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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | pre-patch |  15m  4s | Pre-patch trunk compilation is healthy. |
| {color:green}+1{color} | @author |   0m  0s | The patch does not contain any @author tags. |
| {color:green}+1{color} | tests included |   0m  0s | The patch appears to include 1 new or modified test files. |
| {color:green}+1{color} | javac |   7m 42s | There were no new javac warning messages. |
| {color:green}+1{color} | javadoc |   9m 43s | There were no new javadoc warning messages. |
| {color:green}+1{color} | release audit |   0m 23s | The applied patch does not increase the total number of release audit warnings. |
| {color:red}-1{color} | checkstyle |   1m  6s | The applied patch generated  1 new checkstyle issues (total was 19, now 20). |
| {color:green}+1{color} | whitespace |   0m  0s | The patch has no lines that end in whitespace. |
| {color:green}+1{color} | install |   1m 36s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse |   0m 32s | The patch built with eclipse:eclipse. |
| {color:green}+1{color} | findbugs |   1m 42s | The patch does not introduce any new Findbugs (version 3.0.0) warnings. |
| {color:green}+1{color} | common tests |  22m 48s | Tests passed in hadoop-common. |
| | |  60m 41s | |
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|| Subsystem || Report/Notes ||
| Patch URL | http://issues.apache.org/jira/secure/attachment/12735500/HDFS-8429-003.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / cdbd66b |
| checkstyle |  https://builds.apache.org/job/PreCommit-HDFS-Build/11136/artifact/patchprocess/diffcheckstylehadoop-common.txt |
| hadoop-common test log | https://builds.apache.org/job/PreCommit-HDFS-Build/11136/artifact/patchprocess/testrun_hadoop-common.txt |
| Test Results | https://builds.apache.org/job/PreCommit-HDFS-Build/11136/testReport/ |
| Java | 1.7.0_55 |
| uname | Linux asf904.gq1.ygridcore.net 3.13.0-36-lowlatency #63-Ubuntu SMP PREEMPT Wed Sep 3 21:56:12 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux |
| Console output | https://builds.apache.org/job/PreCommit-HDFS-Build/11136/console |


This message was automatically generated.

> The DomainSocketWatcher thread should not block other threads if it dies
> ------------------------------------------------------------------------
>
>                 Key: HDFS-8429
>                 URL: https://issues.apache.org/jira/browse/HDFS-8429
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.6.0
>            Reporter: zhouyingchao
>            Assignee: zhouyingchao
>         Attachments: HDFS-8429-001.patch, HDFS-8429-002.patch, HDFS-8429-003.patch
>
>
> In our cluster, an application is hung when doing a short circuit read of local hdfs block. By looking into the log, we found the DataNode's DomainSocketWatcher.watcherThread has exited with following log:
> {code}
> ERROR org.apache.hadoop.net.unix.DomainSocketWatcher: Thread[Thread-25,5,main] terminating on unexpected exception
> java.lang.NullPointerException
>         at org.apache.hadoop.net.unix.DomainSocketWatcher$2.run(DomainSocketWatcher.java:463)
>         at java.lang.Thread.run(Thread.java:662)
> {code}
> The line 463 is following code snippet:
> {code}
>          try {
>             for (int fd : fdSet.getAndClearReadableFds()) {
>               sendCallbackAndRemove("getAndClearReadableFds", entries, fdSet,
>                 fd);
>             }
> {code}
> getAndClearReadableFds is a native method which will malloc an int array. Since our memory is very tight, it looks like the malloc failed and a NULL pointer is returned.
> The bad thing is that other threads then blocked in stack like this:
> {code}
> "DataXceiver for client unix:/home/work/app/hdfs/c3prc-micloud/datanode/dn_socket [Waiting for operation #1]" daemon prio=10 tid=0x00007f0c9c086d90 nid=0x8fc3 waiting on condition [0x00007f09b9856000]
>    java.lang.Thread.State: WAITING (parking)
>         at sun.misc.Unsafe.park(Native Method)
>         - parking to wait for  <0x00000007b0174808> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
>         at java.util.concurrent.locks.LockSupport.park(LockSupport.java:156)
>         at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1987)
>         at org.apache.hadoop.net.unix.DomainSocketWatcher.add(DomainSocketWatcher.java:323)
>         at org.apache.hadoop.hdfs.server.datanode.ShortCircuitRegistry.createNewMemorySegment(ShortCircuitRegistry.java:322)
>         at org.apache.hadoop.hdfs.server.datanode.DataXceiver.requestShortCircuitShm(DataXceiver.java:403)
>         at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opRequestShortCircuitShm(Receiver.java:214)
>         at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:95)
>         at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:235)
>         at java.lang.Thread.run(Thread.java:662)
> {code}
> IMO, we should exit the DN so that the users can know that something go  wrong  and fix it.


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