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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-1651) Some improvements in progress reporting
Date Wed, 25 Jul 2007 06:00:31 GMT
Some improvements in progress reporting

                 Key: HADOOP-1651
                 URL: https://issues.apache.org/jira/browse/HADOOP-1651
             Project: Hadoop
          Issue Type: Bug
          Components: mapred
            Reporter: Devaraj Das
            Assignee: Devaraj Das
             Fix For: 0.14.0

Some improvements that can be done:
1) Progress reporting interval can be made slightly large. It is currently 1 second. Propose
to make it 3 seconds to reduce the load on the TaskTracker.
2) Progress reports can potentially be missed. In the loop, if the first attempt at reporting
a progress doesn't go through, it is not retried. The next communication will be a 'ping'.
3) If there is an exception while reporting progress or doing ping, the client should sleep
for sometime before retrying.
4) The TaskUmbilicalProtocol client can always stay connected to the server. Currently, the
default idle timeout on the IPC client is set to 1000 msec (this means that the client will
disconnect if the connection has been idle for 1000 msec). This might lead to unnecessary
tearing-down/setting-up of connections for the TaskUmbilicalProtocol and can be avoided by
having a high idle timeout for this protocol. The idea behind having the idle timeout was
to not hold on to server connections unnecessarily and hence be more scalable when there are
1000s of clients, especially applicable to those protocols involving the JT and the NameNode.
 We don't run into scalability issues with TaskUmbilical protocol since it is limited to a
few Tasks and the corresponding TaskTracker.

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