> On April 14, 2015, 10:01 a.m., Tom Beerbower wrote:
> > Looks good.  Some minor stuff...

Thanks for the review! I'll get those unused refs cleaned up.


- Jonathan


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On April 14, 2015, midnight, Jonathan Hurley wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/33158/
> -----------------------------------------------------------
> 
> (Updated April 14, 2015, midnight)
> 
> 
> Review request for Ambari, Myroslav Papirkovskyy, Nate Cole, Sid Wagle, and 
> Tom Beerbower.
> 
> 
> Bugs: AMBARI-10456
>     https://issues.apache.org/jira/browse/AMBARI-10456
> 
> 
> Repository: ambari
> 
> 
> Description
> -------
> 
> When mapping hosts concurrently with reading information from a cluster, 
> there was a deadlock between the building the cluster health report and 
> mapping the new hosts. 
> 
> A few changes to note here:
> 
> - ClustersImpl uses concurrent maps; there's really no need to keep the 
> internal lock. I removed it in several places where the cluster is guaranteed 
> to be available (such as when using the ID to retrieve the cluster). The 
> concurrent maps guard against concurrent modifications.
> 
> - The Ambari Event Publish was actually synchronous. This not only caused 
> bottlenecks, but also contributed to a secondary deadlock detected while 
> fixing the original issue. It was changed into a single-threaded asynchronous 
> bus. Consumers of this bus should never rely on it to perform its actions in 
> order to perform their own logic, so changing the behavior seemed correct
> 
> 
> Diffs
> -----
> 
>   
> ambari-server/src/main/java/org/apache/ambari/server/events/publishers/AmbariEventPublisher.java
>  96e66a62 
>   
> ambari-server/src/main/java/org/apache/ambari/server/state/cluster/ClustersImpl.java
>  9cf1f5a 
>   
> ambari-server/src/main/java/org/apache/ambari/server/state/services/AmbariServerAlertService.java
>  89f9656 
>   ambari-server/src/test/java/org/apache/ambari/server/events/EventsTest.java 
> 09c335a 
>   
> ambari-server/src/test/java/org/apache/ambari/server/orm/dao/AlertsDAOTest.java
>  9c8ea7d 
>   
> ambari-server/src/test/java/org/apache/ambari/server/state/alerts/AlertEventPublisherTest.java
>  19b5d46 
>   
> ambari-server/src/test/java/org/apache/ambari/server/state/alerts/InitialAlertEventTest.java
>  4e55c49 
>   
> ambari-server/src/test/java/org/apache/ambari/server/state/cluster/ClusterDeadlockTest.java
>  766105d 
>   
> ambari-server/src/test/java/org/apache/ambari/server/state/cluster/ClustersDeadlockTest.java
>  839b25f 
>   
> ambari-server/src/test/java/org/apache/ambari/server/utils/EventBusSynchronizer.java
>  PRE-CREATION 
> 
> Diff: https://reviews.apache.org/r/33158/diff/
> 
> 
> Testing
> -------
> 
> New tests written to cover the deadlocks; existing tests updated for the 
> async event bus.
> 
> 
> Thanks,
> 
> Jonathan Hurley
> 
>

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