On 6/10/11 3:57 PM, MilleBii wrote:
Hadoop is using a map/reduce algorithm, the reduce phase is that phase which collects the results from // execution. It is inherently not possible to parrallelized that phase.
Actually, this is not true at all - it's perfectly ok to have multiple reduce tasks and have them run in parallel.
The only gotcha why it didn't work in this case? The LocalJobRunner - it's limited to run only one map and one reduce task at a time, because it's not meant to be used for anything serious.
In order to have multiple tasks running in parallel you need to use the distributed JobTracker/TaskTracker, even if it's just a single node.
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