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From "Maja Kabiljo (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (GIRAPH-556) Race condition in EdgeStore
Date Fri, 08 Mar 2013 16:48:13 GMT

    [ https://issues.apache.org/jira/browse/GIRAPH-556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13597270#comment-13597270
] 

Maja Kabiljo commented on GIRAPH-556:
-------------------------------------

+1
So when is it legal to call just createVertexEdges()? For example in addVertexRequest(I, V)
we don't initialize them, is that going to cause an issue?
                
> Race condition in EdgeStore
> ---------------------------
>
>                 Key: GIRAPH-556
>                 URL: https://issues.apache.org/jira/browse/GIRAPH-556
>             Project: Giraph
>          Issue Type: Bug
>            Reporter: Alessandro Presta
>            Assignee: Alessandro Presta
>            Priority: Critical
>         Attachments: GIRAPH-556.patch
>
>
> In EdgeStore#addPartitionEdges(), when there is no VertexEdges data structure for a vertex,
we try to insert a newly-created one. If the insertion is successful, we initialize it and
later insert an edge in the synchronized block.
> It can happen that, between creation and initialization, another thread acquires the
lock and tries to add an edge, leading to a NullPointerException for many implementations
of VertexEdges.
> The fix is to create and initialize the structure before we try to insert it.

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