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https://issues.apache.org/jira/browse/GIRAPH-12?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13117011#comment-13117011
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Avery Ching commented on GIRAPH-12:
-----------------------------------
If the default stack size is 1 MB, then for instance if you have 1024 workers,
you are talking about 1 GB just wasted for thread stack space per node. The
aggregate wasted memory would be 1 GB * 1024 = 1 TB, that's a lot of memory =).
The issue is that many clusters (including Yahoo!'s) have are running only
32-bit JVMs. So if you are using 1 GB just for stack space, you only get so
much left for heap (graph + messages). I think this should help quite a bit
until GIRAPH-37 is taken on.
Can you run the unittests against a real Hadoop instance as well? Then I'd say
+1, unless someone disagrees.
> Investigate communication improvements
> --------------------------------------
>
> Key: GIRAPH-12
> URL: https://issues.apache.org/jira/browse/GIRAPH-12
> Project: Giraph
> Issue Type: Improvement
> Components: bsp
> Reporter: Avery Ching
> Assignee: Hyunsik Choi
> Priority: Minor
> Attachments: GIRAPH-12_1.patch, GIRAPH-12_2.patch
>
>
> Currently every worker will start up a thread to communicate with every other
> workers. Hadoop RPC is used for communication. For instance if there are
> 400 workers, each worker will create 400 threads. This ends up using a lot
> of memory, even with the option
> -Dmapred.child.java.opts="-Xss64k".
> It would be good to investigate using frameworks like Netty or custom roll
> our own to improve this situation. By moving away from Hadoop RPC, we would
> also make compatibility of different Hadoop versions easier.
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