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https://issues.apache.org/jira/browse/GEODE-5653?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated GEODE-5653:
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Labels: pull-request-available (was: )
> Race between put of parallel WAN sender event and distributed clear causes
> off-heap orphan
> ------------------------------------------------------------------------------------------
>
> Key: GEODE-5653
> URL: https://issues.apache.org/jira/browse/GEODE-5653
> Project: Geode
> Issue Type: Bug
> Components: offheap, regions, wan
> Reporter: Ryan McMahon
> Priority: Major
> Labels: pull-request-available
>
> A race resulting in an off-heap orphan can occur with Parallel WAN when
> off-heap is enabled on the cache and user's data region. It is the result of
> the put occurring in two distinct steps without proper synchronization. The
> initial value of the region entry is Token.REMOVED_PHASE_1 (step 1) then
> later is replaced with actual GatewaySenderEvent (step 2). If a distributed
> clear is processed between these two steps, it can result in an orphan. More
> details on the race are described below.
> The race is between:
> *Thread 1*. A put of a {{GatewaySenderEvent}} containing an off-heap value to
> one of the WAN "shadow" region's {{BucketRegionQueue}}
> and
> *Thread 2*. A distributed clear on the {{BucketRegionQueue}} containing that
> value
> The race occurs as follows:
> *Thread 1 (Put)*: Put results in a new region entry where the value is
> {{Token.REMOVED_PHASE1}} and put it into the {{CustomEntryConcurrentHashMap}}
> owned by the {{AbstractRegionMap}}.
> *Thread 2 (Clear)*: Iterates through bucket region's segments and clears the
> entries. At this time the value is still {{Token.REMOVED_PHASE_1}}.
> *Thread 1 (Put)*: The {{Token.REMOVED_PHASE_1}} is replaced with the actual
> {{GatewaySenderEvent}} in the region entry. However, the entry was removed
> via the clear above. When the entry is removed from the region, its off-heap
> is orphaned because it is no longer in the {{CustomEntryConcurrentHashMap}}.
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