已解决：hadoop namenode无法启动：Call From node1/192.168.152.31 to node2:8485 failed on connection exception

2020-01-12 16:23:02,893 FATAL org.apache.hadoop.hdfs.server.namenode.FSEditLog: Error: recoverUnfinalizedSegments failed for required journal (JournalAndStream(mgr=QJM to [192.168.152.31:8485, 192.168.152.32:8485, 192.168.152.33:8485], stream=null))
org.apache.hadoop.hdfs.qjournal.client.QuorumException: Got too many exceptions to achieve quorum size 2/3. 3 exceptions thrown:
192.168.152.31:8485: Call From node1/192.168.152.31 to node1:8485 failed on connection exception: java.net.ConnectException: 拒绝连接; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
192.168.152.33:8485: Call From node1/192.168.152.31 to node3:8485 failed on connection exception: java.net.ConnectException: 拒绝连接; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
192.168.152.32:8485: Call From node1/192.168.152.31 to node2:8485 failed on connection exception: java.net.ConnectException: 拒绝连接; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
	at org.apache.hadoop.hdfs.qjournal.client.QuorumException.create(QuorumException.java:81)
	at org.apache.hadoop.hdfs.qjournal.client.QuorumCall.rethrowException(QuorumCall.java:223)
	at org.apache.hadoop.hdfs.qjournal.client.AsyncLoggerSet.waitForWriteQuorum(AsyncLoggerSet.java:142)
	at org.apache.hadoop.hdfs.qjournal.client.QuorumJournalManager.createNewUniqueEpoch(QuorumJournalManager.java:182)
	at org.apache.hadoop.hdfs.qjournal.client.QuorumJournalManager.recoverUnfinalizedSegments(QuorumJournalManager.java:436)
	at org.apache.hadoop.hdfs.server.namenode.JournalSet$8.apply(JournalSet.java:624)
	at org.apache.hadoop.hdfs.server.namenode.JournalSet.mapJournalsAndReportErrors(JournalSet.java:393)
	at org.apache.hadoop.hdfs.server.namenode.JournalSet.recoverUnfinalizedSegments(JournalSet.java:621)
	at org.apache.hadoop.hdfs.server.namenode.FSEditLog.recoverUnclosedStreams(FSEditLog.java:1394)
	at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startActiveServices(FSNamesystem.java:1151)
	at org.apache.hadoop.hdfs.server.namenode.NameNode$NameNodeHAContext.startActiveServices(NameNode.java:1663)
	at org.apache.hadoop.hdfs.server.namenode.ha.ActiveState.enterState(ActiveState.java:61)
	at org.apache.hadoop.hdfs.server.namenode.ha.HAState.setStateInternal(HAState.java:63)
	at org.apache.hadoop.hdfs.server.namenode.ha.StandbyState.setState(StandbyState.java:49)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.transitionToActive(NameNode.java:1541)
	at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.transitionToActive(NameNodeRpcServer.java:1335)
	at org.apache.hadoop.ha.protocolPB.HAServiceProtocolServerSideTranslatorPB.transitionToActive(HAServiceProtocolServerSideTranslatorPB.java:107)
	at org.apache.hadoop.ha.proto.HAServiceProtocolProtos$HAServiceProtocolService$2.callBlockingMethod(HAServiceProtocolProtos.java:4460)
	at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:619)
	at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:975)
	at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2040)
	at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2036)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:422)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1692)
	at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2034)
2020-01-12 16:23:02,894 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 1
2020-01-12 16:23:02,895 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG: 
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start-dfs.sh启动的集群，journalnode（端口8485）是在namenode后启动的。默认情况下namenode启动10s(maxRetries=10, sleepTime=1000)后journalnode还没有启动，就会报上述错误

解决办法：修改core-site.xml中的ipc参数,如果没有就添加如下参数

<!--修改core-site.xml中的ipc参数,防止出现连接journalnode服务ConnectException-->
<property>
    <name>ipc.client.connect.max.retries</name>
    <value>100</value>
    <description>Indicates the number of retries a client will make to establish a server connection.</description>
</property>
<property>
    <name>ipc.client.connect.retry.interval</name>
    <value>10000</value>
    <description>Indicates the number of milliseconds a client will wait for before retrying to establish a server connection.</description>
</property>