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https://issues.apache.org/jira/browse/COCOON-2208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12603216#action_12603216
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Antonio Gallardo commented on COCOON-2208:
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Is not the same as: https://issues.apache.org/jira/browse/COCOON-1985 ?
> Race condition in AbstractCachingProcessingPipeline causes threads to hang.
> ---------------------------------------------------------------------------
>
> Key: COCOON-2208
> URL: https://issues.apache.org/jira/browse/COCOON-2208
> Project: Cocoon
> Issue Type: Bug
> Components: * Cocoon Core
> Affects Versions: 2.1.11
> Reporter: Sylvain Wallez
> Priority: Blocker
>
> There's a race condition in AbstractCachingProcessingPipeline.waitForLock() :
> if "lock" is not null, there is a possibility that the thread that created
> the lock releases it before the current thread starts waiting on it (see
> below). When this happens, the thread waits forever since no thread will ever
> call notify() on the lock.
> The very bad effect is that this progressively blocks the entire thread pool
> of the servlet engine, which ends up rejecting new incoming connections.
> And BTW, calling containsKey() just before get() unneedingly doubles the
> number of lookups.
> {noformat}
> protected boolean waitForLock(Object key) {
> if(transientStore != null) {
> Object lock = null;
> synchronized(transientStore) {
> String lockKey = PIPELOCK_PREFIX+key;
> if(transientStore.containsKey(lockKey)) {
> // cache content is currently being generated, wait for
> other thread
> lock = transientStore.get(lockKey);
> }
> }
> // START OF RACE CONDITION ZONE
> if(lock != null) {
> try {
> // become owner of monitor
> synchronized(lock) {
> // END OF RACE CONDITION ZONE
> lock.wait();
> }
> } catch (InterruptedException e) {
> if(getLogger().isDebugEnabled()) {
> getLogger().debug("Got interrupted
> waiting for other pipeline to finish processing, retrying...",e);
> }
> return false;
> }
> if(getLogger().isDebugEnabled()) {
> getLogger().debug("Other pipeline finished
> processing, retrying to get cached response.");
> }
> return false;
> }
> }
> return true;
> }
> {noformat}
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