Uploaded image for project: 'Cassandra'
  1. Cassandra
  2. CASSANDRA-2105

Fix the read race condition in CFStore for counters

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

Details

    • Bug
    • Status: Resolved
    • Normal
    • Resolution: Fixed
    • 0.8 beta 1
    • None
    • Normal

    Description

      There is a (known) race condition during counter read. Indeed, for standard
      column family there is a small time during which a memtable is both active and
      pending flush and similarly a small time during which a 'memtable' is both
      pending flush and an active sstable. For counters that would imply sometime
      reconciling twice during a read the same counterColumn and thus over-counting.

      Current code changes this slightly by trading the possibility to count twice a
      given counterColumn by the possibility to miss a counterColumn. Thus it trades
      over-counts for under-counts.

      But this is no fix and there is no hope to offer clients any kind of guarantee
      on reads unless we fix this.

      Attachments

        Activity

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

          People

            slebresne Sylvain Lebresne Assign to me
            slebresne Sylvain Lebresne
            Sylvain Lebresne
            Votes:
            1 Vote for this issue
            Watchers:
            2 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved:

              Time Tracking

                Estimated:
                Original Estimate - 4h
                4h
                Remaining:
                Remaining Estimate - 4h
                4h
                Logged:
                Time Spent - Not Specified
                Not Specified

                Slack

                  Issue deployment