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https://issues.apache.org/jira/browse/AMBARI-10456?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Hurley updated AMBARI-10456:
-------------------------------------
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 Publisher 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
was:When mapping hosts concurrently while getting clusters, there's a
deadlock that can occur between {{ClustersImpl}} and {{ClusterImpl}}.
> Ambari Server Deadlock When Mapping Hosts
> -----------------------------------------
>
> Key: AMBARI-10456
> URL: https://issues.apache.org/jira/browse/AMBARI-10456
> Project: Ambari
> Issue Type: Bug
> Affects Versions: 2.0.0
> Reporter: Jonathan Hurley
> Assignee: Jonathan Hurley
> Priority: Critical
> Fix For: 2.1.0
>
> Attachments: dump.txt
>
>
> 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 Publisher 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
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