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From Claudio Martella <>
Subject Re: Number of threads for vertex compute method
Date Wed, 11 Sep 2013 11:46:54 GMT
By default Giraph uses one compute thread for each worker. It uses multiple
threads for IO like Netty etc. The number of compute threads depends on the
number of workers per machine. Imagine you have a machine in your hadoop
cluster with 8 cores and 8 mapper tasks (something like the basic setup).
Then you don't really need a higher number of compute threads per worker,
as your cores will be busy all the time. Increasing the number of compute
threads is useful when you have a setup where you have one worker per
machine. In that case you'd have one compute thread per core.

On Wed, Sep 11, 2013 at 12:00 PM, Christian Krause <> wrote:

> Hi,
> by default, how many threads are used for the compute method? I thought
> that Giraph would automatically use multiple threads by default, but then I
> stumbled onto this log message:
> 2013-09-11 11:51:44,501 INFO org.apache.giraph.graph.GraphTaskManager: execute: 6 partitions
to process with 1 compute thread(s), originally 1 thread(s) on superstep 7
> Does this really mean that it uses only one thread?
> Cheers,
> Christian

   Claudio Martella

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