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From "Amar Kamat (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-3524) JobTracker's processHeartbeat() should not call System.currentTimeMillis() everytime
Date Tue, 10 Jun 2008 09:09:45 GMT
JobTracker's processHeartbeat() should not call System.currentTimeMillis() everytime
------------------------------------------------------------------------------------

                 Key: HADOOP-3524
                 URL: https://issues.apache.org/jira/browse/HADOOP-3524
             Project: Hadoop Core
          Issue Type: Improvement
          Components: mapred
            Reporter: Amar Kamat


Consider the following
{code:title=JobTracker.java|borderStyle=solid}
private synchronized boolean processHeartbeat(
                                                TaskTrackerStatus trackerStatus, boolean initialContact)
{
    String trackerName = trackerStatus.getTrackerName();
    trackerStatus.setLastSeen(System.currentTimeMillis());
{code}
Here, the call to {{System.currentTimeMillis()}} on every call to {{JobTracker.processHeartbeat()}}
might prove costly. While testing/benchmarking HADOOP-2119, we recorded that the JobTracker
was able to serve ~130 tasks/sec. So that means we might make ~130 calls to {{System.currentTimeMillis()}}
per second. I think in these cases (_last-seen-status_ etc) such a high level of accuracy
in terms of timestamp is unnecessary and hence can be avoided.

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