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https://issues.apache.org/jira/browse/GIRAPH-730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13749010#comment-13749010
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Eli Reisman commented on GIRAPH-730:
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Hi Chaun,
I'm having a bit of trouble finding the concurrency issue here. The
LOCAL_RESOURCES is a common resource map that is initialized once per AM
instance (which is hopefully a singleton at this point!) and reused, unchanged,
for each task launched. It is this object that is returned from
getTaskResourceMap to buildContainerLaunchContext, which returns the launch
context, populating the ContainerLaunchContext before any threads are run or
submitted. from then on, the method is just returning a reference to the same
map each call.
If there is a concurrency issue, it might be more likely attributed to
buildLaunchContainerContext. But I'm not really seeing one.
If you are certain this is a concurrency issue and the syncronization fix is
the only thing verified to work, I'd try this:
I think the null check at the top of getTaskResourceMap is atomic by nature,
you could just add a syncronization block around the map construction portion.
I think returning the unchanging (and essentially immutable) map singleton in
the loop of containers after that will be thread safe.
> GiraphApplicationMaster race condition in resource loading
> ----------------------------------------------------------
>
> Key: GIRAPH-730
> URL: https://issues.apache.org/jira/browse/GIRAPH-730
> Project: Giraph
> Issue Type: Bug
> Affects Versions: 1.0.0
> Environment: Giraph with Yarn
> Reporter: Chuan Lei
> Assignee: Chuan Lei
> Attachments: GIRAPH-730.v1.patch
>
>
> In GiraphApplicationMaster.java, getTaskResourceMap function is not
> multi-thread safe, which causes the application master fail to distribute the
> resources (jar, configuration file, etc.) to each container.
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