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Posted to dev@giraph.apache.org by "Alessandro Presta (JIRA)" <ji...@apache.org> on 2013/03/08 08:12:13 UTC
[jira] [Updated] (GIRAPH-556) Race condition in EdgeStore
[ https://issues.apache.org/jira/browse/GIRAPH-556?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Alessandro Presta updated GIRAPH-556:
-------------------------------------
Attachment: GIRAPH-556.patch
Fixes the bug by always initializing a newly-created VertexEdges before inserting it.
At the same time, I also remove some leftover checks for null pointer in VertexEdges#initialize() implementations: we never (and should never) call initialize with a null Iterable (what I originally thought was the cause of this bug).
> Race condition in EdgeStore
> ---------------------------
>
> Key: GIRAPH-556
> URL: https://issues.apache.org/jira/browse/GIRAPH-556
> Project: Giraph
> Issue Type: Bug
> Reporter: 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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