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Posted to hdfs-dev@hadoop.apache.org by "zhouyingchao (JIRA)" <ji...@apache.org> on 2015/05/19 13:26:59 UTC
[jira] [Created] (HDFS-8429) Death of watcherThread making other
local read blocked
zhouyingchao created HDFS-8429:
----------------------------------
Summary: Death of watcherThread making other local read blocked
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
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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