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https://issues.apache.org/jira/browse/POOL-411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17696484#comment-17696484
]
Gary D. Gregory commented on POOL-411:
--------------------------------------
It would be easy enough to do this:
{noformat}
diff --git
a/src/main/java/org/apache/commons/pool2/impl/GenericKeyedObjectPool.java
b/src/main/java/org/apache/commons/pool2/impl/GenericKeyedObjectPool.java
index 0697ef8..26034a6 100644
--- a/src/main/java/org/apache/commons/pool2/impl/GenericKeyedObjectPool.java
+++ b/src/main/java/org/apache/commons/pool2/impl/GenericKeyedObjectPool.java
@@ -834,19 +834,21 @@
try {
lock.lock();
final ObjectDeque<T> objectDeque = poolMap.get(k);
- final long numInterested =
objectDeque.getNumInterested().decrementAndGet();
- if (numInterested == 0 && objectDeque.getCreateCount().get() == 0)
{
- // Potential to remove key
- // Upgrade to write lock
- lock.unlock();
- lock = keyLock.writeLock();
- lock.lock();
- if (objectDeque.getCreateCount().get() == 0 &&
objectDeque.getNumInterested().get() == 0) {
- // NOTE: Keys must always be removed from both poolMap and
- // poolKeyList at the same time while protected by
- // keyLock.writeLock()
- poolMap.remove(k);
- poolKeyList.remove(k);
+ if (objectDeque != null) {
+ final long numInterested =
objectDeque.getNumInterested().decrementAndGet();
+ if (numInterested == 0 && objectDeque.getCreateCount().get()
== 0) {
+ // Potential to remove key
+ // Upgrade to write lock
+ lock.unlock();
+ lock = keyLock.writeLock();
+ lock.lock();
+ if (objectDeque.getCreateCount().get() == 0 &&
objectDeque.getNumInterested().get() == 0) {
+ // NOTE: Keys must always be removed from both poolMap
and
+ // poolKeyList at the same time while protected by
+ // keyLock.writeLock()
+ poolMap.remove(k);
+ poolKeyList.remove(k);
+ }
}
}
} finally {
{noformat}
BUT, I would want to know if we are missing the application of a lock
elsewhere. The above NPE proofing would not hurt even if we found and fixed a
locking bug.
> Potential 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
>
> 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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