有一段時間沒有啓動過Hbase,重新啓動HBase數據庫時候，發現有一個節點沒有啓動，查看其啓動日誌，可以看到它拋出了ClockOutOfSyncException異常，具體的異常如下所示：
2017-04-23 20:18:28,975 FATAL [regionserver/node2/192.168.8.119:16020] regionserver.HRegionServer: Master rejected startup because clock is out of sync
org.apache.hadoop.hbase.ClockOutOfSyncException: org.apache.hadoop.hbase.ClockOutOfSyncException: Server node2,16020,1492949885855 has been rejected; Reported time is too far out of sync with master. Time difference of 71531ms > max allowed of 30000msat org.apache.hadoop.hbase.master.ServerManager.checkClockSkew(ServerManager.java:388)
at org.apache.hadoop.hbase.master.ServerManager.regionServerStartup(ServerManager.java:262)
at org.apache.hadoop.hbase.master.MasterRpcServices.regionServerStartup(MasterRpcServices.java:322)
atorg.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos$RegionServerStatusService$2.callBlockingMethod(RegionServerStatusProtos.java:8615)
at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2117)
at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:104)
at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:133)
at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:108)
at java.lang.Thread.run(Thread.java:745)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteException.java:106)
at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteException.java:95)
at org.apache.hadoop.hbase.protobuf.ProtobufUtil.getRemoteException(ProtobufUtil.java:325)
at org.apache.hadoop.hbase.regionserver.HRegionServer.reportForDuty(HRegionServer.java:2271)
at org.apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer.java:893)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.hadoop.hbase.ipc.RemoteWithExtrasException(org.apache.hadoop.hbase.ClockOutOfSyncException): org.apache.hadoop.hbase.ClockOutOfSyncException: Server node2,16020,1492949885855 has been rejected; Reported time is too far out of sync with master. Time difference of 71531ms > max allowed of 30000ms
at org.apache.hadoop.hbase.master.ServerManager.checkClockSkew(ServerManager.java:388)
at org.apache.hadoop.hbase.master.ServerManager.regionServerStartup(ServerManager.java:262)
at org.apache.hadoop.hbase.master.MasterRpcServices.regionServerStartup(MasterRpcServices.java:322)
at org.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos$RegionServerStatusService$2.callBlockingMethod(RegionServerStatusProtos.java:8615)
at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2117)
at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:104)
at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:133)
at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:108)
at java.lang.Thread.run(Thread.java:745)
at org.apache.hadoop.hbase.ipc.RpcClientImpl.call(RpcClientImpl.java:1235)
at org.apache.hadoop.hbase.ipc.AbstractRpcClient.callBlockingMethod(AbstractRpcClient.java:217)
at org.apache.hadoop.hbase.ipc.AbstractRpcClient$BlockingRpcChannelImplementation.callBlockingMethod(AbstractRpcClient.java:318)
atorg.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos$RegionServerStatusService$BlockingStub.regionServerStartup(RegionServerStatusProtos.java:8982)
at org.apache.hadoop.hbase.regionserver.HRegionServer.reportForDuty(HRegionServer.java:2269)... 2 more
2017-04-23 20:18:28,979 FATAL [regionserver/node2/192.168.8.119:16020] regionserver.HRegionServer: ABORTING region server node2,16020,1492949885855: Unhandled: org.apache.hadoop.hbase.ClockOutOfSyncException: Server node2,16020,1492949885855 has been rejected; Reported time is too far out of sync with master. Time difference of 71531ms > max allowed of 30000ms
at org.apache.hadoop.hbase.master.ServerManager.checkClockSkew(ServerManager.java:388)
at org.apache.hadoop.hbase.master.ServerManager.regionServerStartup(ServerManager.java:262)
at org.apache.hadoop.hbase.master.MasterRpcServices.regionServerStartup(MasterRpcServices.java:322)
atorg.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos$RegionServerStatusService$2.callBlockingMethod(RegionServerStatusProtos.java:8615)
at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2117)
at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:104)
at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:133)
at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:108)
at java.lang.Thread.run(Thread.java:745)
org.apache.hadoop.hbase.ClockOutOfSyncException: org.apache.hadoop.hbase.ClockOutOfSyncException: Server node2,16020,1492949885855 has been rejected; Reported time is too far out of sync with master. Time difference of 71531ms > max allowed of 30000ms
at org.apache.hadoop.hbase.master.ServerManager.checkClockSkew(ServerManager.java:388)
at org.apache.hadoop.hbase.master.ServerManager.regionServerStartup(ServerManager.java:262)
at org.apache.hadoop.hbase.master.MasterRpcServices.regionServerStartup(MasterRpcServices.java:322)
atorg.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos$RegionServerStatusService$2.callBlockingMethod(RegionServerStatusProtos.java:8615)
at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2117)
at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:104)
at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:133)
at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:108)
at java.lang.Thread.run(Thread.java:745)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteException.java:106)
at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteException.java:95)
at org.apache.hadoop.hbase.protobuf.ProtobufUtil.getRemoteException(ProtobufUtil.java:325)
at org.apache.hadoop.hbase.regionserver.HRegionServer.reportForDuty(HRegionServer.java:2271)
at org.apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer.java:893)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.hadoop.hbase.ipc.RemoteWithExtrasException(org.apache.hadoop.hbase.ClockOutOfSyncException): org.apache.hadoop.hbase.ClockOutOfSyncException: Server node2,16020,1492949885855 has been rejected; Reported time is too far out of sync with master. Time difference of 71531ms > max allowed of 30000ms
at org.apache.hadoop.hbase.master.ServerManager.checkClockSkew(ServerManager.java:388)
at org.apache.hadoop.hbase.master.ServerManager.regionServerStartup(ServerManager.java:262)
at org.apache.hadoop.hbase.master.MasterRpcServices.regionServerStartup(MasterRpcServices.java:322)
at org.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos$RegionServerStatusService$2.callBlockingMethod(RegionServerStatusProtos.java:8615)
at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2117)
at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:104)
at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:133)
at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:108)
at java.lang.Thread.run(Thread.java:745)
at org.apache.hadoop.hbase.ipc.RpcClientImpl.call(RpcClientImpl.java:1235)
at org.apache.hadoop.hbase.ipc.AbstractRpcClient.callBlockingMethod(AbstractRpcClient.java:217)
atorg.apache.hadoop.hbase.ipc.AbstractRpcClient$BlockingRpcChannelImplementation.callBlockingMethod(AbstractRpcClient.java:318)
atorg.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos$RegionServerStatusService$BlockingStub.regionServerStartup(RegionServerStatusProtos.java:8982)
at org.apache.hadoop.hbase.regionserver.HRegionServer.reportForDuty(HRegionServer.java:2269 )
通過日誌分析，可以發現Master節點和node2節點之間的連接用時71531ms，超過了默認的時間30000ms，具體爲什麼會
連接超時，可能是硬件原因，也可能是軟件問題。現在解決辦法就是在Master節點配置連接時間的屬性，時間設置大一些
在Master節點的HBase配置文件hbase-siter.xml中添加連接時長的屬性，然後重新啓動Hbase就行了。
<property>
<name>hbase.master.maxclockskew</name>
<value>120000</value>
</property>