You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@giraph.apache.org by "Claudio Martella (JIRA)" <ji...@apache.org> on 2013/02/19 00:53:12 UTC
[jira] [Resolved] (GIRAPH-462) Multithreading breaks out-of-core
graph
[ https://issues.apache.org/jira/browse/GIRAPH-462?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Claudio Martella resolved GIRAPH-462.
-------------------------------------
Resolution: Fixed
> Multithreading breaks out-of-core graph
> ---------------------------------------
>
> Key: GIRAPH-462
> URL: https://issues.apache.org/jira/browse/GIRAPH-462
> Project: Giraph
> Issue Type: Bug
> Reporter: Alessandro Presta
> Priority: Critical
> Attachments: GIRAPH-461.patch
>
>
> [~cmartella] pointed out this issue: when using multithreaded computation in conjunction with out-of-core graph, we incur in a race condition. The compute threads share the same DiskBackedPartitionStore, whose getPartition() method is not meant to be thread-safe. When two threads request two out-of-core partitions concurrently, they both try to load it to the same slot.
> The result is that we can lose the reference to one of the two partitions (which will not be written back to disk) and we can incur in a NullPointerException when both threads are trying to offload the currently loaded partition to disk.
> I ran this test to confirm the issue:
> https://gist.github.com/4429628
> All tests pass except the one that uses both out-of-core graph and multiple compute threads.
> The error is the following:
> https://gist.github.com/4429650
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira