Details
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Bug
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Status: Patch Available
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Major
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Resolution: Unresolved
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None
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Description
Found when debugging HIVE-20103, that a reader arriving when another reader is active can postpone a writer from obtaining a write-lock.
This is fundamentally bad for the DAGImpl as useful progress can only happen when the writeLock is held.
public void handle(DAGEvent event) { ... try { writeLock.lock();
java.lang.Thread.State: WAITING (parking) at sun.misc.Unsafe.park(Native Method) - parking to wait for <0x00007efb02246f40> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199) at java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.lock(ReentrantReadWriteLock.java:943) at org.apache.tez.dag.app.dag.impl.DAGImpl.handle(DAGImpl.java:1162) at org.apache.tez.dag.app.dag.impl.DAGImpl.handle(DAGImpl.java:149) at org.apache.tez.dag.app.DAGAppMaster$DagEventDispatcher.handle(DAGAppMaster.java:2251) at org.apache.tez.dag.app.DAGAppMaster$DagEventDispatcher.handle(DAGAppMaster.java:2242) at org.apache.tez.common.AsyncDispatcher.dispatch(AsyncDispatcher.java:180) at org.apache.tez.common.AsyncDispatcher$1.run(AsyncDispatcher.java:115) at java.lang.Thread.run(Thread.java:745)
while read-lock is passed around between
at org.apache.tez.dag.app.dag.impl.DAGImpl.getDAGStatus(DAGImpl.java:901)
at org.apache.tez.dag.app.dag.impl.DAGImpl.getDAGStatus(DAGImpl.java:940)
at org.apache.tez.dag.api.client.DAGClientHandler.getDAGStatus(DAGClientHandler.java:73)
calls.
Attachments
Attachments
Issue Links
- is related to
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- Closed
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