[jira] [Created] (HBASE-9087) Handlers being blocked during reads

["Pablo Medina (JIRA)" <ji...@apache.org>]

Pablo Medina created HBASE-9087:
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             Summary: Handlers being blocked during reads
                 Key: HBASE-9087
                 URL: https://issues.apache.org/jira/browse/HBASE-9087
             Project: HBase
          Issue Type: Bug
          Components: Performance
    Affects Versions: 0.94.7
            Reporter: Pablo Medina
            Priority: Critical


I'm having a lot of handlers (90 - 300 aprox) being blocked when reading rows. They are blocked during changedReaderObserver registration.

Lars Hofhansl suggests to change the implementation of changedReaderObserver from CopyOnWriteList to ConcurrentHashMap.

Here is a stack trace: 

"IPC Server handler 99 on 60020" daemon prio=10 tid=0x0000000041c84000 nid=0x2244 waiting on condition [0x00007ff51fefd000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000c5c13ae8> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:156)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:811)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:842)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1178)
        at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:186)
        at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:262)
        at java.util.concurrent.CopyOnWriteArrayList.addIfAbsent(CopyOnWriteArrayList.java:553)
        at java.util.concurrent.CopyOnWriteArraySet.add(CopyOnWriteArraySet.java:221)
        at org.apache.hadoop.hbase.regionserver.Store.addChangedReaderObserver(Store.java:1085)
        at org.apache.hadoop.hbase.regionserver.StoreScanner.<init>(StoreScanner.java:138)
        at org.apache.hadoop.hbase.regionserver.Store.getScanner(Store.java:2077)
        at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.<init>(HRegion.java:3755)
        at org.apache.hadoop.hbase.regionserver.HRegion.instantiateRegionScanner(HRegion.java:1804)
        at org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:1796)
        at org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:1771)
        at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:4776)
        at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:4750)
        at org.apache.hadoop.hbase.regionserver.HRegionServer.get(HRegionServer.java:2152)
        at org.apache.hadoop.hbase.regionserver.HRegionServer.multi(HRegionServer.java:3700)
        at sun.reflect.GeneratedMethodAccessor26.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.hadoop.hbase.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:320)
        at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1426)
      

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