[jira] [Commented] (NIFI-2395) PersistentProvenanceRepository Deadlocks caused by a blocked journal merge

["ASF subversion and git services (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-2395?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15552569#comment-15552569 ] 

ASF subversion and git services commented on NIFI-2395:
-------------------------------------------------------

Commit 83fdced7c340ad25f78597be49c69d3b2fdbb8e3 in nifi's branch refs/heads/0.x from [~boardm26]
[ https://git-wip-us.apache.org/repos/asf?p=nifi.git;h=83fdced ]

NIFI-2429 changes needed after cherry-picking NIFI-2395 from master


> PersistentProvenanceRepository Deadlocks caused by a blocked journal merge
> --------------------------------------------------------------------------
>
>                 Key: NIFI-2395
>                 URL: https://issues.apache.org/jira/browse/NIFI-2395
>             Project: Apache NiFi
>          Issue Type: Bug
>          Components: Core Framework
>    Affects Versions: 0.6.0, 0.7.0
>            Reporter: Brian Davis
>            Assignee: Joseph Witt
>            Priority: Blocker
>             Fix For: 1.0.0, 1.0.0-Beta
>
>
> I have a nifi instance that I have been running for about a week and has deadlocked at least 3 times during this time.  When I say deadlock the whole nifi instance stops doing any progress on flowfiles.  I looked at the stack trace and there are a lot of threads stuck doing tasks in the PersistentProvenanceRepository.  Looking at the code I think this is what is happening:
> There is a ReadWriteLock that all the reads are waiting for a write.  The write is in the loop:
> {code}
>                 while (journalFileCount > journalCountThreshold || repoSize > sizeThreshold) {
>                     // if a shutdown happens while we are in this loop, kill the rollover thread and break
>                     if (this.closed.get()) {
>                         if (future != null) {
>                             future.cancel(true);
>                         }
>                         break;
>                     }
>                     if (repoSize > sizeThreshold) {
>                         logger.debug("Provenance Repository has exceeded its size threshold; will trigger purging of oldest events");
>                         purgeOldEvents();
>                         journalFileCount = getJournalCount();
>                         repoSize = getSize(getLogFiles(), 0L);
>                         continue;
>                     } else {
>                         // if we are constrained by the number of journal files rather than the size of the repo,
>                         // then we will just sleep a bit because another thread is already actively merging the journals,
>                         // due to the runnable that we scheduled above
>                         try {
>                             Thread.sleep(100L);
>                         } catch (final InterruptedException ie) {
>                         }
>                     }
>                     logger.debug("Provenance Repository is still behind. Keeping flow slowed down "
>                             + "to accommodate. Currently, there are {} journal files ({} bytes) and "
>                             + "threshold for blocking is {} ({} bytes)", journalFileCount, repoSize, journalCountThreshold, sizeThreshold);
>                     journalFileCount = getJournalCount();
>                     repoSize = getSize(getLogFiles(), 0L);
>                 }
>                 logger.info("Provenance Repository has now caught up with rolling over journal files. Current number of "
>                         + "journal files to be rolled over is {}", journalFileCount);
>             }
> {code}
> My nifi is at the sleep indefinitely.  The reason my nifi cannot move forward is because of the thread doing the merge is stopped.  The thread doing the merge is at:
> {code}
> accepted = eventQueue.offer(new Tuple<>(record, blockIndex), 10, TimeUnit.MILLISECONDS);
> {code}
> so the queue is full.  
> What I believe happened is that the callables created here:
> {code}
>                             final Callable<Object> callable = new Callable<Object>() {
>                                 @Override
>                                 public Object call() throws IOException {
>                                     while (!eventQueue.isEmpty() || !finishedAdding.get()) {
>                                         final Tuple<StandardProvenanceEventRecord, Integer> tuple;
>                                         try {
>                                             tuple = eventQueue.poll(10, TimeUnit.MILLISECONDS);
>                                         } catch (final InterruptedException ie) {
>                                             continue;
>                                         }
>                                         if (tuple == null) {
>                                             continue;
>                                         }
>                                         indexingAction.index(tuple.getKey(), indexWriter, tuple.getValue());
>                                     }
>                                     return null;
>                                 }
> {code}
> finish before the offer adds its first event because I do not see any Index Provenance Events threads.  My guess is the while loop condition is wrong and should be && instead of ||.
> I upped the thread count for the index creation from 1 to 3 to see if that helps.  I can tell you if that helps later this week.



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