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Hadoop, mail # dev - Mumak's Speculative Execution

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Mumak's Speculative Execution
Nan Zhu 2010-10-11, 16:17
Hi, all

I'm a student in University of Nebraska, Lincoln, I'm interested in the
project of mumak and I truly need a simulator of hadoop for my work

I read the source code of hadoop-mapred as well as the mumak itself,

I find that in the slides in http://www.slideshare.net/hadoopusergroup/mumak,
it announces that mumak cannot simulate speculative execution currently, but
in SimulatorJobTracker class, the function of heartbeat() contains such a
statement "TaskScheduler.assign(task)", since assign() will call the
implementation of JobInProgress class, it can surely call the
findspeculativeTask(), etc, so ***I think mumak should have the ability of
simulating speculative execution***. To verify it, I insert some statement
in SimulatorJobTracker.java to print the number of SpeculativeTasks, the
value keep to be zero, it seems that mumak really have done nothing about
speculative execution strategy.

It's strange, I'm confusing on this situation. Can anyone tell me the reason
of unable to simulate speculative execution in mumak?

Thank you very much!