ConnectionLoss for/hbase + Connection由peer重置？

Question

我正在我的本地机器(伪分布式)上运行Hadoop MapReduce作业,该作业读取和写入HBase.我间歇性地得到一个错误,这会破坏工作,即使计算机一个人没有运行其他重要进程 - 请参阅下面的日志.作业死后,ZooKeeper Dump的输出看起来像这样,运行失败后客户端数量增加:

HBase is rooted at /hbase
Master address: SS-WS-M102:60000
Region server holding ROOT: SS-WS-M102:60020
Region servers:
 SS-WS-M102:60020
Quorum Server Statistics:
 ss-ws-m102:2181
  Zookeeper version: 3.3.3-cdh3u0--1, built on 03/26/2011 00:20 GMT
  Clients:
   /192.168.40.120:58484[1]\(queued=0,recved=39199,sent=39203)
   /192.168.40.120:37129[1]\(queued=0,recved=162,sent=162)
   /192.168.40.120:58485[1]\(queued=0,recved=39282,sent=39316)
   /192.168.40.120:58488[1]\(queued=0,recved=39224,sent=39226)
   /192.168.40.120:58030[0]\(queued=0,recved=1,sent=0)
   /192.168.40.120:58486[1]\(queued=0,recved=39248,sent=39267)

我的开发团队目前正在使用CDH3U0发行版,因此HBase 0.90.1 - 这是一个在最近发布的版本中解决的问题吗？或者我应该对当前设置做些什么？我是否应该期望重新启动ZK并定期杀死客户端？我愿意接受任何合理的选择,让我的工作能够始终如一地完成.

2012-06-27 13:01:07,289 INFO org.apache.zookeeper.ClientCnxn: Opening socket connection to server SS-WS-M102/192.168.40.120:2181
2012-06-27 13:01:07,289 INFO org.apache.zookeeper.ClientCnxn: Socket connection established to SS-WS-M102/192.168.40.120:2181, initiating session
2012-06-27 13:01:07,290 WARN org.apache.zookeeper.ClientCnxn: Session 0x0 for server SS-WS-M102/192.168.40.120:2181, unexpected error, closing socket connection and attempting reconnect
java.io.IOException: Connection reset by peer
    at sun.nio.ch.FileDispatcher.read0(Native Method)
    at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:21)
    at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:202)
    at sun.nio.ch.IOUtil.read(IOUtil.java:169)
    at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:243)
    at org.apache.zookeeper.ClientCnxn$SendThread.doIO(ClientCnxn.java:858)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1130)
[lines above repeat 6 more times]
2012-06-27 13:01:17,890 ERROR org.apache.hadoop.hbase.mapreduce.TableInputFormat: org.apache.hadoop.hbase.ZooKeeperConnectionException: org.apache.hadoop.hbase.ZooKeeperConnectionException: org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase
    at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getZooKeeperWatcher(HConnectionManager.java:991)
    at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.setupZookeeperTrackers(HConnectionManager.java:302)
    at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.<init>(HConnectionManager.java:293)
    at org.apache.hadoop.hbase.client.HConnectionManager.getConnection(HConnectionManager.java:156)
    at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:167)
    at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:145)
    at org.apache.hadoop.hbase.mapreduce.TableInputFormat.setConf(TableInputFormat.java:91)
    at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:62)
    at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:605)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:322)
    at org.apache.hadoop.mapred.Child$4.run(Child.java:268)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:396)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1115)
    at org.apache.hadoop.mapred.Child.main(Child.java:262)
Caused by: org.apache.hadoop.hbase.ZooKeeperConnectionException: org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase
    at org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher.<init>(ZooKeeperWatcher.java:147)
    at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getZooKeeperWatcher(HConnectionManager.java:989)
    ... 15 more
Caused by: org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase
    at org.apache.zookeeper.KeeperException.create(KeeperException.java:90)
    at org.apache.zookeeper.KeeperException.create(KeeperException.java:42)
    at org.apache.zookeeper.ZooKeeper.create(ZooKeeper.java:637)
    at org.apache.hadoop.hbase.zookeeper.ZKUtil.createAndFailSilent(ZKUtil.java:902)
    at org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher.<init>(ZooKeeperWatcher.java:133)
    ... 16 more

Answer 1

我过去也遇到过类似的问题。在使用 HBase/Hadoop 的很多时候，您会看到一些错误消息，这些消息并没有指出您遇到的真正问题，因此您必须发挥创意。

这是我发现的，它可能适用也可能不适用于您：

您是否打开了许多与表的连接并在完成后关闭它们？如果您在映射器或减速器中执行扫描/获取，则在 MR 作业中可能会发生这种情况（如果可以避免的话，我认为您不想这样做）。

另外，如果我的映射器或减速器大量写入同一行，有时我会遇到类似的问题。尝试分布写入或最小化写入以减少此问题。

如果您详细了解 MR 工作的性质也会有所帮助。它有什么作用？你有示例代码吗？