[jira] [Created] (CONNECTORS-1720) Fatal Error due to NPE in RepriorizationTracker

["Maunel Bach (Jira)" <ji...@apache.org>]

Maunel Bach created CONNECTORS-1720:
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             Summary: Fatal Error due to NPE in RepriorizationTracker
                 Key: CONNECTORS-1720
                 URL: https://issues.apache.org/jira/browse/CONNECTORS-1720
             Project: ManifoldCF
          Issue Type: Bug
    Affects Versions: ManifoldCF 2.22
            Reporter: Maunel Bach


A couple of times a week our ManifoldCF instance logged a stacktrace like that:
{code:bash}
2022-07-06T14:04:39,297 FATAL [Set priority thread] org.apache.manifoldcf.crawlerthreads: Error tossed: null
java.lang.NullPointerException: null
	at org.apache.manifoldcf.crawler.reprioritizationtracker.ReprioritizationTracker$PreloadKey.hashCode(ReprioritizationTracker.java:460) ~[mcf-pull-agent.jar:?]
	at java.util.HashMap.hash(HashMap.java:339) ~[?:?]
	at java.util.HashMap.get(HashMap.java:552) ~[?:?]
	at org.apache.manifoldcf.crawler.reprioritizationtracker.ReprioritizationTracker.addPreloadRequest(ReprioritizationTracker.java:234) ~[mcf-pull-agent.jar:?]
	at org.apache.manifoldcf.crawler.system.PriorityCalculator.makePreloadRequest(PriorityCalculator.java:123) ~[mcf-pull-agent.jar:?]
	at org.apache.manifoldcf.crawler.system.ManifoldCF.writeDocumentPriorities(ManifoldCF.java:1247) ~[mcf-pull-agent.jar:?]
	at org.apache.manifoldcf.crawler.system.SetPriorityThread.run(SetPriorityThread.java:141) ~[mcf-pull-agent.jar:?]{code}

We tracked it down to a not null safe {{hashCode()}} implementation of the private {{PreloadRequest}} class consuming the first entry of the array {{binNames}}. The specifics of the array is an implementation detail of a connector base class. Potentially array might contain {{null}} values at least for the {{JiraRepositoryConnector}} and more critical for the {{WebcrawlerConnector}}.

As a solution we fixed the {{hashCode()}} implementation in our own code base which did the trick. We should consider to fix this bug in the Apache repository as well. But of course the fix does not help improve the extraction and usage of the {{binName}} itself.

We stumbled over this bug because the jobs on our ManifoldCF instance got stuck. Though we cannot be sure whether there was a correlation between this greater incident and the fatal error here because that was not the only fatal bug we fixed to get ManifoldCF up an running again. But the topic "repriorization" indicates that a bit.



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