[jira] [Created] (HDFS-7187) DomainSocketWatcher thread crashes causing datanode to leak connection threads

["Maxim Ivanov (JIRA)" <ji...@apache.org>]

Maxim Ivanov created HDFS-7187:
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             Summary: DomainSocketWatcher thread crashes causing datanode to leak connection threads
                 Key: HDFS-7187
                 URL: https://issues.apache.org/jira/browse/HDFS-7187
             Project: Hadoop HDFS
          Issue Type: Bug
            Reporter: Maxim Ivanov


It seems that DomainSocketWatcher crashes, which makes all those short circuit threads to wait forever:

{code}
Exception in thread "Thread-22" java.util.ConcurrentModificationException
        at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1115)
        at java.util.TreeMap$ValueIterator.next(TreeMap.java:1160)
        at org.apache.hadoop.net.unix.DomainSocketWatcher$1.run(DomainSocketWatcher.java:465)
        at java.lang.Thread.run(Thread.java:745)
{code}

In the meantime DataXceiver threads look like this (their number grows up to connection threads limit):

{code}
"DataXceiver for client unix:/var/run/hadoop-hdfs/datanode50010.socket [Waiting for operation #1]" daemon prio=10 tid=0x00007fb3c14d3800 nid=0x997e waiting on condition [0x00007fb2a1d25000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0000000744d1d600> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:867)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1197)
        at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:214)
        at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290)
        at org.apache.hadoop.net.unix.DomainSocketWatcher.add(DomainSocketWatcher.java:286)
        at org.apache.hadoop.hdfs.server.datanode.ShortCircuitRegistry.createNewMemorySegment(ShortCircuitRegistry.java:283)
        at org.apache.hadoop.hdfs.server.datanode.DataXceiver.requestShortCircuitShm(DataXceiver.java:386)
        at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opRequestShortCircuitShm(Receiver.java:172)
        at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:92)
        at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:229)
        at java.lang.Thread.run(Thread.java:745)
{code}




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