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MapReduce, mail # user - What's the basic idea of pseudo-distributed Hadoop ?


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Re: What's the basic idea of pseudo-distributed Hadoop ?
Kai Voigt 2012-09-14, 06:08
Hello.

Am 14.09.2012 um 08:03 schrieb Jason Yang <[EMAIL PROTECTED]>:

> I have a question about how does the pseudo-distributed Hadoop cluster work:
>
> As many map tasks are submitted to the pseudo-distributed Hadoop cluster, does the hadoop run each mapper in sequence ? or does it run these mappers in different threads or something could be parallel?

pseudo-distributed mode is a one node cluster. You have a namenode, a jobtracker, and a single datanode and tasktracker running. You can verify with "jps" command.

The default setting is that a tasktracker can run up to two map and reduce tasks in parallel (mapred.tasktracker.map.tasks.maximum and mapred.tasktracker.reduce.tasks.maximum), so you will actually see some concurrency on your one machine.

Kai

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Kai Voigt
[EMAIL PROTECTED]