[GitHub] merlimat opened a new pull request #1154: Fixed use of static synchronized in LoadManagerShared

[GitBox <gi...@apache.org>]

merlimat opened a new pull request #1154: Fixed use of static synchronized in LoadManagerShared
URL: https://github.com/apache/incubator-pulsar/pull/1154
 
 
   ### Motivation
   
   This is an attempt to fix the issue in `ReplicatorTest` ( #1138 )  which is causing many CI builds to intermittently fail.
   
   The `LoadManagerShared` is synchronizing on a static method to reuse the a single hash set for cache purposes. I have seen a thread stuck on that during a repeated testing:
   
   ```
   "pulsar-2997-2" #6897 prio=5 os_prio=31 tid=0x00007fdd33898800 nid=0x6830f waiting for monitor entry [0x000070000bb07000]
      java.lang.Thread.State: BLOCKED (on object monitor)
   	at org.apache.pulsar.broker.loadbalance.impl.LoadManagerShared.applyNamespacePolicies(LoadManagerShared.java:90)
   	- waiting to lock <0x00000006c0bc1250> (a java.lang.Class for org.apache.pulsar.broker.loadbalance.impl.LoadManagerShared)
   	at org.apache.pulsar.broker.loadbalance.impl.ModularLoadManagerImpl.selectBrokerForAssignment(ModularLoadManagerImpl.java:705)
   	- locked <0x000000078cf4e308> (a java.util.HashSet)
   	at org.apache.pulsar.broker.loadbalance.impl.ModularLoadManagerWrapper.getLeastLoaded(ModularLoadManagerWrapper.java:68)
   	at org.apache.pulsar.broker.namespace.NamespaceService.getLeastLoadedFromLoadManager(NamespaceService.java:463)
   	at org.apache.pulsar.broker.namespace.NamespaceService.searchForCandidateBroker(NamespaceService.java:338)
   	at org.apache.pulsar.broker.namespace.NamespaceService.lambda$4(NamespaceService.java:301)
   	at org.apache.pulsar.broker.namespace.NamespaceService$$Lambda$113/1109341011.run(Unknown Source)
   	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
   	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
   	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
   	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
   	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
   	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
   	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
   	at java.lang.Thread.run(Thread.java:745)
   ```
   
   ### Modifications
   
   Made the sets thread local and removed the mutex.
   
   

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