Major Description
I was running IntegrationTestDDLMasterFailover on distributed cluster when i notice this. Here is relevant part of master's jstack:
"ProcedureExecutor-1" daemon prio=10 tid=0x00007fd2d407f800 nid=0x3332 waiting for monitor entry [0x00007fd2c2834000] java.lang.Thread.State: BLOCKED (on object monitor) at org.apache.hadoop.hbase.master.TableNamespaceManager.releaseExclusiveLock(TableNamespaceManager.java:157) - waiting to lock <0x0000000725c36a48> (a org.apache.hadoop.hbase.master.TableNamespaceManager) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.releaseLock(CreateNamespaceProcedure.java:216) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.releaseLock(CreateNamespaceProcedure.java:43) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:842) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:794) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$400(ProcedureExecutor.java:75) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor$2.run(ProcedureExecutor.java:479) Locked ownable synchronizers: - <0x000000072574b330> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync) "ProcedureExecutor-3" daemon prio=10 tid=0x00007fd2d41e5800 nid=0x3334 waiting on condition [0x00007fd2c2632000] java.lang.Thread.State: TIMED_WAITING (parking) at sun.misc.Unsafe.park(Native Method) - parking to wait for <0x000000072574b330> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync) at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226) at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireNanos(AbstractQueuedSynchronizer.java:929) at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireNanos(AbstractQueuedSynchronizer.java:1245) at java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.tryLock(ReentrantReadWriteLock.java:1115) at org.apache.hadoop.hbase.master.TableNamespaceManager.acquireExclusiveLock(TableNamespaceManager.java:150) - locked <0x0000000725c36a48> (a org.apache.hadoop.hbase.master.TableNamespaceManager) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.acquireLock(CreateNamespaceProcedure.java:210) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.acquireLock(CreateNamespaceProcedure.java:43) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeRollback(ProcedureExecutor.java:941) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:821) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:794) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$400(ProcedureExecutor.java:75) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor$2.run(ProcedureExecutor.java:479) Locked ownable synchronizers: - None Found one Java-level deadlock: ============================= "ProcedureExecutor-3": waiting for ownable synchronizer 0x000000072574b330, (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync), which is held by "ProcedureExecutor-1" "ProcedureExecutor-1": waiting to lock monitor 0x00007fd2cc328908 (object 0x0000000725c36a48, a org.apache.hadoop.hbase.master.TableNamespaceManager), which is held by "ProcedureExecutor-3" Java stack information for the threads listed above: =================================================== "ProcedureExecutor-3": at sun.misc.Unsafe.park(Native Method) - parking to wait for <0x000000072574b330> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync) at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226) at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireNanos(AbstractQueuedSynchronizer.java:929) at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireNanos(AbstractQueuedSynchronizer.java:1245) at java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.tryLock(ReentrantReadWriteLock.java:1115) at org.apache.hadoop.hbase.master.TableNamespaceManager.acquireExclusiveLock(TableNamespaceManager.java:150) - locked <0x0000000725c36a48> (a org.apache.hadoop.hbase.master.TableNamespaceManager) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.acquireLock(CreateNamespaceProcedure.java:210) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.acquireLock(CreateNamespaceProcedure.java:43) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeRollback(ProcedureExecutor.java:941) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:821) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:794) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$400(ProcedureExecutor.java:75) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor$2.run(ProcedureExecutor.java:479) "ProcedureExecutor-1": at org.apache.hadoop.hbase.master.TableNamespaceManager.releaseExclusiveLock(TableNamespaceManager.java:157) - waiting to lock <0x0000000725c36a48> (a org.apache.hadoop.hbase.master.TableNamespaceManager) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.releaseLock(CreateNamespaceProcedure.java:216) at org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure.releaseLock(CreateNamespaceProcedure.java:43) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:842) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execLoop(ProcedureExecutor.java:794) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$400(ProcedureExecutor.java:75) at org.apache.hadoop.hbase.procedure2.ProcedureExecutor$2.run(ProcedureExecutor.java:479) Found 1 deadlock.
I will try to dig more info about why this happened logs not showing much.