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From Steven Xu <xu...@neusoft.com>
Subject [HDFS] DFSClient does not closing a closed socket resulting in thousand of CLOSE_WAIT sockets with HDP 2.1/HBase 0.98.0/Hadoop/2.4.0
Date Fri, 29 Aug 2014 09:26:07 GMT
Hello Hadoopers,

When I run HDP 2.1/HBase 0.98.0/Hadoop/2.4.0, I always got the fatal
problem: DFSClient does not closing a closed socket resulting in thousand of
CLOSE_WAIT sockets. Have you guys got same issue, if that please share to
me? Thanks a lot. I also create a issue HDFS-6973 for this.

 

HBase as HDFS Client dose not close a dead connection with the datanode.
This resulting in over 30K+ CLOSE_WAIT and at some point HBase can not
connect to the datanode because too many mapped sockets from one host to
another on the same port:50010. 
After I restart all RSs, the count of CLOSE_WAIT will increase always.
$ netstat -an|grep CLOSE_WAIT|wc -l
2545
netstat -nap|grep CLOSE_WAIT|grep 6569|wc -l
2545
ps -ef|grep 6569
hbase 6569 6556 21 Aug25 ? 09:52:33 /opt/jdk1.6.0_25/bin/java
-Dproc_regionserver -XX:OnOutOfMemoryError=kill -9 %p -Xmx1000m
-XX:+UseConcMarkSweepGC
I aslo have reviewed these issues:
HDFS-5697 <https://issues.apache.org/jira/browse/HDFS-5697> 
HDFS-5671 <https://issues.apache.org/jira/browse/HDFS-5671> 
HDFS-1836 <https://issues.apache.org/jira/browse/HDFS-1836> 
 <https://issues.apache.org/jira/browse/HBASE-9393> HBASE-9393
I found in HBase 0.98/Hadoop 2.4.0 source codes of these patchs have been
added.
But I donot understand why HBase 0.98/Hadoop 2.4.0 also have this isssue.
Please check. Thanks a lot.
These codes have been added into
BlockReaderFactory.getRemoteBlockReaderFromTcp(). Another bug maybe lead my
problem,


BlockReaderFactory.java

 

// Some comments here

  private BlockReader getRemoteBlockReaderFromTcp() throws IOException {

    if (LOG.isTraceEnabled()) {

      LOG.trace(this + ": trying to create a remote block reader from a " +

          "TCP socket");

    }

    BlockReader blockReader = null;

    while (true) {

      BlockReaderPeer curPeer = null;

      Peer peer = null;

      try {

        curPeer = nextTcpPeer();

        if (curPeer == null) break;

        if (curPeer.fromCache) remainingCacheTries--;

        peer = curPeer.peer;

        blockReader = getRemoteBlockReader(peer);

        return blockReader;

      } catch (IOException ioe) {

        if (isSecurityException(ioe)) {

          if (LOG.isTraceEnabled()) {

            LOG.trace(this + ": got security exception while constructing "
+

                "a remote block reader from " + peer, ioe);

          }

          throw ioe;

        }

        if ((curPeer != null) && curPeer.fromCache) {

          // Handle an I/O error we got when using a cached peer.  These are

          // considered less serious, because the underlying socket may be

          // stale.

          if (LOG.isDebugEnabled()) {

            LOG.debug("Closed potentially stale remote peer " + peer, ioe);

          }

        } else {

          // Handle an I/O error we got when using a newly created peer.

          LOG.warn("I/O error constructing remote block reader.", ioe);

          throw ioe;

        }

      } finally {

        if (blockReader == null) {

          IOUtils.cleanup(LOG, peer);

        }

      }

    }

    return null;

  }

 

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