Uploaded image for project: 'Cassandra'
  1. Cassandra
  2. CASSANDRA-12961

LCS needlessly checks for L0 STCS candidates multiple times

Agile BoardAttach filesAttach ScreenshotBulk Copy AttachmentsBulk Move AttachmentsVotersWatch issueWatchersCreate sub-taskConvert to sub-taskMoveLinkCloneLabelsUpdate Comment AuthorReplace String in CommentUpdate Comment VisibilityDelete Comments
    XMLWordPrintableJSON

Details

    Description

      It's very likely that the check for L0 STCS candidates (if L0 is falling behind) can be moved outside of the loop, or at very least made so that it's not called on each loop iteration:

              for (int i = generations.length - 1; i > 0; i--)
              {
                  List<SSTableReader> sstables = getLevel(i);
                  if (sstables.isEmpty())
                      continue; // mostly this just avoids polluting the debug log with zero scores
                  // we want to calculate score excluding compacting ones
                  Set<SSTableReader> sstablesInLevel = Sets.newHashSet(sstables);
                  Set<SSTableReader> remaining = Sets.difference(sstablesInLevel, cfs.getTracker().getCompacting());
                  double score = (double) SSTableReader.getTotalBytes(remaining) / (double)maxBytesForLevel(i, maxSSTableSizeInBytes);
                  logger.trace("Compaction score for level {} is {}", i, score);
      
                  if (score > 1.001)
                  {
                      // before proceeding with a higher level, let's see if L0 is far enough behind to warrant STCS
                      CompactionCandidate l0Compaction = getSTCSInL0CompactionCandidate();
                      if (l0Compaction != null)
                          return l0Compaction;
      ......
      

      Attachments

        Activity

          This comment will be Viewable by All Users Viewable by All Users
          Cancel

          People

            vusal.ahmadoglu Vusal Ahmadoglu Assign to me
            jjirsa Jeff Jirsa
            Vusal Ahmadoglu
            Jeff Jirsa
            Votes:
            0 Vote for this issue
            Watchers:
            3 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved:

              Slack

                Issue deployment