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https://issues.apache.org/jira/browse/HBASE-1314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12707567#action_12707567
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Andrew Purtell commented on HBASE-1314:
---------------------------------------

Getting back to the issue at hand, the problem here is the master takes some 
recovery action even though the regionserver is actually still up and serving 
requests. Waiting two minutes to clobber its log won't make a difference, the 
log will be just as corrupt. 

> master sees HRS znode expire and splits log while the HRS is still running 
> and accepting edits
> ----------------------------------------------------------------------------------------------
>
>                 Key: HBASE-1314
>                 URL: https://issues.apache.org/jira/browse/HBASE-1314
>             Project: Hadoop HBase
>          Issue Type: Bug
>    Affects Versions: 0.20.0
>            Reporter: Andrew Purtell
>             Fix For: 0.20.0
>
>
> ZK session expiration related problem. HRS loses its ephemeral node while it 
> is still up and running and accepting edits. Master sees it go away and 
> starts splitting its logs while edits are still being written. After this, 
> all reconstruction logs have to be manually removed from the region 
> directories or the regions will never deploy (CRC errors). I think on HDFS 
> edits would be lost, not corrupted. (I am using a HBase root on local file 
> system.) 
> HRS ZK session expires, causing its znode to go away:
> 2009-04-07 03:50:39,953 INFO org.apache.hadoop.hbase.master.ServerManager: 
> localhost.localdomain_1239068648333_60020 znode expired
> 2009-04-07 03:50:40,565 DEBUG org.apache.hadoop.hbase.master.HMaster: 
> Processing todo: ProcessServerShutdown of 
> localhost.localdomain_1239068648333_60020
> 2009-04-07 03:50:40,637 INFO 
> org.apache.hadoop.hbase.master.RegionServerOperation: process shutdown of 
> server localhost.localdomain_1239068648333_60020: logSplit: false, 
> rootRescanned: false, numberOfMetaRegions: 1, onlineMetaRegions.size(): 1
> But here we have the HRS still reporting in, triggering a 
> LeaseStillHeldException:
> 2009-04-07 03:50:40,826 INFO org.apache.hadoop.ipc.HBaseServer: IPC Server 
> handler 2 on 60000, call regionServerReport(address: 127.0.0.1:60020, 
> startcode: 1239068648333, load: (requests=14, regions=7, usedHeap=582, 
> maxHeap=888), [Lorg.apache.hadoop.hbase.HMsg;@6da21389, 
> [Lorg.apache.hadoop.hbase.HRegionInfo;@2bb0bf9a) from 127.0.0.1:39238: error: 
> org.apache.hadoop.hbase.Leases$LeaseStillHeldException
> org.apache.hadoop.hbase.Leases$LeaseStillHeldException
>         at 
> org.apache.hadoop.hbase.master.ServerManager.regionServerReport(ServerManager.java:198)
>         at 
> org.apache.hadoop.hbase.master.HMaster.regionServerReport(HMaster.java:601)
>         at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
>         at 
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>         at java.lang.reflect.Method.invoke(Method.java:597)
>         at org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:632)
>         at 
> org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:909)
> And log splitting starts anyway:
> 2009-04-07 03:50:41,139 INFO org.apache.hadoop.hbase.regionserver.HLog: 
> Splitting 3 log(s) in 
> file:/data/hbase/log_localhost.localdomain_1239068648333_60020
> 2009-04-07 03:50:41,139 DEBUG org.apache.hadoop.hbase.regionserver.HLog: 
> Splitting 1 of 3: 
> file:/data/hbase/log_localhost.localdomain_1239068648333_60020/hlog.dat.1239075060711
> [...]

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