[HDFS-9054] Race condition on yieldCount in FSDirectory.java

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Won't Fix
• Affects Version/s: 2.7.0
• Component/s: namenode
• Assignee: yunjiong zhao
• Reporter: yunjiong zhao
• Created: 11/Sep/15 07:47
• Updated: 14/Sep/15 02:40
• Resolved: 14/Sep/15 02:40

Description

getContentSummaryInt only held read lock, and it called fsd.addYieldCount which may cause race condition:

  private static ContentSummary getContentSummaryInt(FSDirectory fsd,
      INodesInPath iip) throws IOException {
    fsd.readLock();
    try {
      INode targetNode = iip.getLastINode();
      if (targetNode == null) {
        throw new FileNotFoundException("File does not exist: " + iip.getPath());
      }
      else {
        // Make it relinquish locks everytime contentCountLimit entries are
        // processed. 0 means disabled. I.e. blocking for the entire duration.
        ContentSummaryComputationContext cscc =
            new ContentSummaryComputationContext(fsd, fsd.getFSNamesystem(),
                fsd.getContentCountLimit(), fsd.getContentSleepMicroSec());
        ContentSummary cs = targetNode.computeAndConvertContentSummary(cscc);
        fsd.addYieldCount(cscc.getYieldCount());
        return cs;
      }
    } finally {
      fsd.readUnlock();
    }
  }