Some improvements in progress reporting
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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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