[HBASE-6309] [MTTR] Do NN operations outside of the ZK EventThread in SplitLogManager

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Abandoned
• Affects Version/s: 0.92.1, 0.94.0, 0.95.2
• Component/s: MTTR
• Assignee: Unassigned
• Reporter: Jean-Daniel Cryans
• Created: 02/Jul/12 23:52
• Updated: 13/Jun/22 16:46
• Resolved: 13/Jun/22 16:46

Description

We found this issue during the leap second cataclysm which prompted a distributed splitting of all our logs.

I saw that none of the RS were splitting after some time while the master was showing that it wasn't even 30% done. jstack'ing I saw this:

"main-EventThread" daemon prio=10 tid=0x00007f6ce46d8800 nid=0x5376 in
Object.wait() [0x00007f6ce2ecb000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:485)
        at org.apache.hadoop.ipc.Client.call(Client.java:1093)
        - locked <0x00000005fdd661a0> (a org.apache.hadoop.ipc.Client$Call)
        at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:226)
        at $Proxy9.rename(Unknown Source)
        at sun.reflect.GeneratedMethodAccessor29.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:82)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:59)
        at $Proxy9.rename(Unknown Source)
        at org.apache.hadoop.hdfs.DFSClient.rename(DFSClient.java:759)
        at org.apache.hadoop.hdfs.DistributedFileSystem.rename(DistributedFileSystem.java:253)
        at org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.moveRecoveredEditsFromTemp(HLogSplitter.java:553)
        at org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.moveRecoveredEditsFromTemp(HLogSplitter.java:519)
        at org.apache.hadoop.hbase.master.SplitLogManager$1.finish(SplitLogManager.java:138)
        at org.apache.hadoop.hbase.master.SplitLogManager.getDataSetWatchSuccess(SplitLogManager.java:431)
        at org.apache.hadoop.hbase.master.SplitLogManager.access$1200(SplitLogManager.java:95)
        at org.apache.hadoop.hbase.master.SplitLogManager$GetDataAsyncCallback.processResult(SplitLogManager.java:1011)
        at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:571)
        at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:497)

We are effectively bottlenecking on doing NN operations and whatever else is happening in GetDataAsyncCallback. It was so bad that on our 100 offline cluster it took a few hours for the master to process all the incoming ZK events while the actual splitting took a fraction of that time.

I'm marking this as critical and against 0.96 but depending on how involved the fix is we might want to backport.

Issue Links

• is required by: HBASE-5843 Improve HBase MTTR - Mean Time To Recover