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From "Prabhu Joseph (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-6797) Improvement in the fix of Mapreduce-6684
Date Wed, 19 Oct 2016 11:39:58 GMT
Prabhu Joseph created MAPREDUCE-6797:
----------------------------------------

             Summary: Improvement in the fix of Mapreduce-6684
                 Key: MAPREDUCE-6797
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6797
             Project: Hadoop Map/Reduce
          Issue Type: Bug
          Components: jobhistoryserver
    Affects Versions: 2.4.0, 2.8.0
            Reporter: Prabhu Joseph
            Priority: Critical


Description:

There is one more piece of code in HistoryFileManager where Synchronized keyword on HistoryFileInfo
need to be removed. The JobHistoryServer contention issue is hit on our environment where
stacktrace (attached) shows the HistoryFileManager$JobListCache.addIfAbsent unnecessarily
waiting to lock on HistoryFileInfo.

Synchronized on isMovePending and didMoveFail has been removed by Mapreduce-6684.

{code}
HistoryFileInfo firstValue = cache.get(key);
    synchronized(firstValue) {  ---------------> Synchronized is not needed here
              if (firstValue.isMovePending()) {
                if(firstValue.didMoveFail() && 
                    firstValue.jobIndexInfo.getFinishTime() <= cutoff) {
                  cache.remove(key);
                  //Now lets try to delete it
                  try {
                    firstValue.delete();
                  } catch (IOException e) {
                    LOG.error("Error while trying to delete history files" +
                    " that could not be moved to done.", e);
                  }
                } else {
                  LOG.warn("Waiting to remove " + key
                      + " from JobListCache because it is not in done yet.");
                }
              } else {
                cache.remove(key);
              }
            }

{code}


{code}

Note: stacktrace is from hadoop-2.4.0 version and the problem exists in latest hadoop as well

"2144820863@qtp-313351300-38156" daemon prio=10 tid=0x0000000001e13800 nid=0xf133 waiting
for monitor entry [0x00007f7c1d8dd000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager$JobListCache.addIfAbsent(HistoryFileManager.java:226)
        - waiting to lock <0x000000040145c4d8> (a org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager$HistoryFileInfo)
        at org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager.scanIntermediateDirectory(HistoryFileManager.java:825)
        at org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager.access$200(HistoryFileManager.java:82)
        at org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager$UserLogDir.scanIfNeeded(HistoryFileManager.java:280)
        - locked <0x0000000400375388> (a org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager$UserLogDir)
        at org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager.scanIntermediateDirectory(HistoryFileManager.java:792)
        at org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager.getAllFileInfo(HistoryFileManager.java:920)
        at org.apache.hadoop.mapreduce.v2.hs.CachedHistoryStorage.getAllPartialJobs(CachedHistoryStorage.java:156)
        at org.apache.hadoop.mapreduce.v2.hs.JobHistory.getAllJobs(JobHistory.java:235)
{code}



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