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https://issues.apache.org/jira/browse/NIFI-526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14503382#comment-14503382
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Michael Moser commented on NIFI-526:
------------------------------------
I read this code differently. Between the first and second if(), timeToPersist
has not changed and can't change outside the writeLock. However,
System.currentTimeMillis() could have changed and can only increase, so the
second if() will be guaranteed to be true as long as the first if() was true.
> GetHTTP may not release writeLock
> ---------------------------------
>
> Key: NIFI-526
> URL: https://issues.apache.org/jira/browse/NIFI-526
> Project: Apache NiFi
> Issue Type: Bug
> Components: Extensions
> Affects Versions: 0.0.2
> Reporter: Mark Latimer
> Priority: Minor
> Labels: beginner, newbie
> Fix For: 0.1.0
>
>
> GetHTTP onTrigger process contains a path that will obtain and not release
> the writeLock.
> This happens if enough time elapses between the first and second check of
> timeToPersist.
> Also the readLock locked and unlocked with no meaningful work in between.
> {code:title=GetHTTP.java|borderStyle=solid}
> if ((etag != null || lastModified != null) &&
> readLock.tryLock()) {
> try {
> //first check of timeToPersist against current time
> if (timeToPersist < System.currentTimeMillis()) {
> readLock.unlock();
> //obtain writeLock
> writeLock.lock();
> //check time to persist again, this result may be
> different
> //if the result is different because enough time
> has elapsed the lock is not released
> if (timeToPersist < System.currentTimeMillis()) {
> try {
>
> ...
>
> } finally {
> readLock.lock();
> //release writeLock only if the second
> check of timeToPresist is before now.
> writeLock.unlock();
> }
> }
> }
> } finally {
> readLock.unlock();
> }
> }
> {code}
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