> On Aug. 5, 2016, 12:36 p.m., Jonathan Hurley wrote:
> > This is an AmbariEvent which has it's own EventBus; however the bus is an 
> > asynchronous, single-threaded bus. This means that it's possible for a 
> > heartbeat to be received in between when this event is broadcast and when 
> > it's received by your subscriber method. 
> > 
> > If the problem only happens on registration, I think this solution is OK. 
> > But if a heartbeat from an agent can cause problems as well, then there is 
> > still a slight chance that the timing here could still reproduce the bug.
> 
> Laszlo Puskas wrote:
>     Thanks for the observation. The problem only occurred on registration; 
> Even if the host is registered before the host remove event is processed, the 
> registering host will have a new id, thus the removal won't interfere with 
> the new method.

In my previous comment i erroneously stated, that the new method won't cause 
issues due to the new id the host will be assigned when it registers back.
Actually the code will behave correctly because available hosts are stored in a 
list; thus the code will find the proper record to remove. (the older entry 
will be found first in the list)


- Laszlo


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On Aug. 4, 2016, 3:22 p.m., Laszlo Puskas wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/50753/
> -----------------------------------------------------------
> 
> (Updated Aug. 4, 2016, 3:22 p.m.)
> 
> 
> Review request for Ambari, Jonathan Hurley, Robert Nettleton, Sandor Magyari, 
> and Sebastian Toader.
> 
> 
> Bugs: AMBARI-18005
>     https://issues.apache.org/jira/browse/AMBARI-18005
> 
> 
> Repository: ambari
> 
> 
> Description
> -------
> 
> When a host is removed from the cluster and later from ambari there's a 
> chance the agent registers back to the ambari server before the agent is 
> stopped.
> Stopping the machine running the agent without the host being deleted again 
> leads to an inconsistent state in the ambari-server due to cached state.
> Resolution:
> The cached resources get cleared on host delete event.
> 
> 
> Diffs
> -----
> 
>   
> ambari-server/src/main/java/org/apache/ambari/server/state/host/HostImpl.java 
> a757010 
>   
> ambari-server/src/main/java/org/apache/ambari/server/topology/TopologyManager.java
>  0190478 
> 
> Diff: https://reviews.apache.org/r/50753/diff/
> 
> 
> Testing
> -------
> 
> Suceesfully tested. (Manually)
> Unit tests in progress.
> 
> 
> Thanks,
> 
> Laszlo Puskas
> 
>

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