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https://issues.apache.org/jira/browse/POOL-411?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phil Steitz reopened POOL-411:
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The added test case has failed at least once now. I think there is a problem
with register/deregister protection of pools. Very low probability, but the
following seems like it could happen:
Thread 1
# Enter register
# get the read lock
# get a non-null, existing pool
Thread 2
# Clear the pool
# Deregister and remove it
Thread 1
# Register interest in the now orphaned pool
This may be possible because deregister can escalate to write lock while others
are holding read locks. The Thread 2 actions have to happen between two
instructions in register (when it gets the pool and when it increments its
numInterested).
> NPE when deregistering key at end of borrow
> -------------------------------------------
>
> Key: POOL-411
> URL: https://issues.apache.org/jira/browse/POOL-411
> Project: Commons Pool
> Issue Type: Task
> Affects Versions: 2.11.1
> Reporter: Richard Eckart de Castilho
> Priority: Major
> Fix For: 2.12.0
>
>
> There is a potential for an NPE happening in the finally block of
> borrowObject:
> {noformat}
> Caused by: java.lang.NullPointerException: Cannot invoke
> "org.apache.commons.pool2.impl.GenericKeyedObjectPool$ObjectDeque.getNumInterested()"
> because "objectDeque" is null
> at
> org.apache.commons.pool2.impl.GenericKeyedObjectPool.deregister(GenericKeyedObjectPool.java:821)
> at
> org.apache.commons.pool2.impl.GenericKeyedObjectPool.borrowObject(GenericKeyedObjectPool.java:507)
> at
> org.apache.commons.pool2.impl.GenericKeyedObjectPool.borrowObject(GenericKeyedObjectPool.java:350)
>
> {noformat}
> From reading the code, it seems this could happen e.g. if a pool is
> concurrently cleared while a borrow is in progress.
> Not sure what a proper solution here would be. Maybe deregister should
> silently do nothing if poolMap.get(k) returns null?
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