namenode由于jn写入超时异常

namenode异常信息：

2020-06-03 04:44:42,313 FATAL org.apache.hadoop.hdfs.server.namenode.FSEditLog: Error: flush failed for required journal (JournalAndStream(mgr=QJM to [1xx:8485, xxx:8485, xxx:8485], stream=QuorumOutputStream starting at txid 47431233))
java.io.IOException: Timed out waiting 20000ms for a quorum of nodes to respond.
        at org.apache.hadoop.hdfs.qjournal.client.AsyncLoggerSet.waitForWriteQuorum(AsyncLoggerSet.java:137)
        at org.apache.hadoop.hdfs.qjournal.client.QuorumOutputStream.flushAndSync(QuorumOutputStream.java:107)
        at org.apache.hadoop.hdfs.server.namenode.EditLogOutputStream.flush(EditLogOutputStream.java:113)
        at org.apache.hadoop.hdfs.server.namenode.EditLogOutputStream.flush(EditLogOutputStream.java:107)
        at org.apache.hadoop.hdfs.server.namenode.JournalSet$JournalSetOutputStream$8.apply(JournalSet.java:533)
        at org.apache.hadoop.hdfs.server.namenode.JournalSet.mapJournalsAndReportErrors(JournalSet.java:393)
        at org.apache.hadoop.hdfs.server.namenode.JournalSet.access$100(JournalSet.java:57)
        at org.apache.hadoop.hdfs.server.namenode.JournalSet$JournalSetOutputStream.flush(JournalSet.java:529)
        at org.apache.hadoop.hdfs.server.namenode.FSEditLog.logSync(FSEditLog.java:707)
        at org.apache.hadoop.hdfs.server.namenode.FSEditLogAsync.run(FSEditLogAsync.java:188)
        at java.lang.Thread.run(Thread.java:748)

解决办法：

在hdfs-site.xml添加如下配置：

<property>
<!-- EditLog会被切割为很多段，每一段称为一个segment，Namenode发起新写入editlog的RPC调用，会使用startLogSegment方法，该参数表示发起新segment的超时时间 -->
    <name>dfs.qjournal.start-segment.timeout.ms</name>
    <value>90000</value>
</property>
<property>
    <name>dfs.qjournal.select-input-streams.timeout.ms</name>
    <value>90000</value>
</property>
<property>
<!--写入超时时间 -->
    <name>dfs.qjournal.write-txns.timeout.ms</name>
    <value>90000</value>
</property>

在core-site.xml

ipc.client.connect.timeout = 90000

2、关闭zk优先同步日志功能

forceSync=no

借鉴：

https://www.cppentry.com/bencandy.php?fid=118&id=195295

https://blog.csdn.net/xjping0794/article/details/77836543