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Posted to dev@lucene.apache.org by "Andrey Kudryavtsev (JIRA)" <ji...@apache.org> on 2017/10/12 10:37:00 UTC

[jira] [Created] (SOLR-11474) Endless loop and OOM in PeerSync

Andrey Kudryavtsev created SOLR-11474:
-----------------------------------------

             Summary: Endless loop and OOM in PeerSync
                 Key: SOLR-11474
                 URL: https://issues.apache.org/jira/browse/SOLR-11474
             Project: Solr
          Issue Type: Bug
      Security Level: Public (Default Security Level. Issues are Public)
            Reporter: Andrey Kudryavtsev


After problem discussed in SOLR-11459, I restarted cluster and got OOM on start. 

PeerSync#handleVersionsWithRanges contains this logic: 

{code}
    while (otherUpdatesIndex >= 0) {
      // we have run out of ourUpdates, pick up all the remaining versions from the other versions
      if (ourUpdatesIndex < 0) {
        String range = otherVersions.get(otherUpdatesIndex) + "..." + otherVersions.get(0);
        rangesToRequest.add(range);
        totalRequestedVersions += otherUpdatesIndex + 1;
        break;
      }

      // stop when the entries get old enough that reorders may lead us to see updates we don't need
      if (!completeList && Math.abs(otherVersions.get(otherUpdatesIndex)) < ourLowThreshold) break;

      if (ourUpdates.get(ourUpdatesIndex).longValue() == otherVersions.get(otherUpdatesIndex).longValue()) {
        ourUpdatesIndex--;
        otherUpdatesIndex--;
      } else if (Math.abs(ourUpdates.get(ourUpdatesIndex)) < Math.abs(otherVersions.get(otherUpdatesIndex))) {
        ourUpdatesIndex--;
      } else {
        long rangeStart = otherVersions.get(otherUpdatesIndex);
        while ((otherUpdatesIndex < otherVersions.size())
            && (Math.abs(otherVersions.get(otherUpdatesIndex)) < Math.abs(ourUpdates.get(ourUpdatesIndex)))) {
          otherUpdatesIndex--;
          totalRequestedVersions++;
        }
        // construct range here
        rangesToRequest.add(rangeStart + "..." + otherVersions.get(otherUpdatesIndex + 1));
      }
    }
{code}

If at some point there will be
{code} ourUpdates.get(ourUpdatesIndex) = -otherVersions.get(otherUpdatesIndex) {code}
loop will never end. It will same string again and again into {{rangesToRequest}} until process runs out of memory.






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