[jira] [Closed] (GEODE-8671) Two threads calling get and retrieve the same PdxInstance, resulting in corruption

["Dick Cavender (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GEODE-8671?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dick Cavender closed GEODE-8671.
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> Two threads calling get and retrieve the same PdxInstance, resulting in corruption
> ----------------------------------------------------------------------------------
>
>                 Key: GEODE-8671
>                 URL: https://issues.apache.org/jira/browse/GEODE-8671
>             Project: Geode
>          Issue Type: Improvement
>          Components: regions
>            Reporter: Dan Smith
>            Assignee: Jianxia Chen
>            Priority: Major
>              Labels: blocks-1.14.0​, pull-request-available
>             Fix For: 1.12.2, 1.13.2, 1.14.0, 1.15.0
>
>
> Even if copy-on-read is set to true, two threads calling get on a partitioned region can end up with the same PdxInstance object.
> This is problematic because some PdxInstances methods are not thread safe. Although the underlying bytes are immutatable, the PDXInstance has a ByteSource with a position field that changes. That means two threads doing serialization or calling toString on the PdxInstance could result in one or more threads getting a corrupt read.
> It looks like they are ending up with the same instance because of the behavior in LocalRegion.optimizedGetObject. We use futures to make sure there is only 1 get that goes through, and both threads receive the same value.
>     
> Ending up in optimizedGetObject requires a race with the put, because if the value was in the cache at the beginning of the get it would be returned earlier in the get process.
> I put a test that reproduces this issue here -   https://github.com/upthewaterspout/geode/pull/new/feature/pdx-instances-shared



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