What is the importance of the Acknowledge button after re-index?

Chris Solgat

We have noticed some behaviors from JIRA after running a reindex over the weekend.  Most notably, the occurrences of 

Tried to reopen the IndexReader, but it threw AlreadyClosedException. Opening a fresh IndexReader.

have been increasing.  With the way that we roll our log file, we keep 30 days worth of catalina.out files, that roll every restart.  The past three weeks, we have initiated the re-index through a script that runs at 3am.  We have noticed that the log reference above has increased from 25 times for the week ending 3/29/15, to 94 entries for the week ending 4/5/15, to 369 entries for a log file that ended 4/7/15, and our current log file that started on 4/7 has 541 entries. 

The script that we run uses the API to login and start the reindex.  The question I ask is about the Acknowledge button that appears when a re-index completes.  What does it do?  Does it clear some cache or processes that are holding onto the index readers?  I'm pretty sure that the Acknowledgement is not happening in the script.  We believe that this is causing performance problems for our environment.

crf

None.  Well, almost none.

Long running tasks get registered in a component called the TaskManager (funnily enough).  Multiple users could potentially be watching the same task's progress – for example, if another administrator went to the indexing page after you had kicked one off, then they would join you in watching its progress rather than be offered the choice to kick off one of their own while yours was already running.  Each of your web browsers would regularly refresh the page so you could entertain yourself with the progress bar.

But what about when it finishes?  If we threw away the data as soon as we showed you that it had reached 100%, then only one of the user's would see the information.

The "Acknowledge" button tells JIRA that the TaskManager doesn't need to hold onto the results anymore.  Once you have acknowledged them, they are discarded and other requests to that URL will not be able to display them.  But it does not actually do anything that "completes" the indexing; that is long since done.

The message about reopening an index reader may sound alarming, but it isn't usually anything to worry about.  It is an artifact of how JIRA's indexing code handles the Lucene index reader.  There is a sort of cache of the current index reader, but this can be closed at any time by a new write to the index.  We check for whether or not this has happened before trying to use the existing reader, but there is no way to do that check and request that the index reader be reopened in a single, atomic operation, so we can get unlucky and lose this race.  The message is reporting that this happened, but most of the time it is completely innocuous.

It is a little surprising that you are seeing that message with increasing frequency, but I would not be too worried about it unless you have another symptom that something is wrong, such as leaked file handles, increasing use of disk space well beyond the reported size of the index files, and so on.