GitHub user CrazyJvm opened a pull request:
https://github.com/apache/spark/pull/403
misleading task number of groupByKey
"By default, this uses only 8 parallel tasks to do the grouping." is a big
misleading. Please refer to https://github.com/apache/spark/pull/389
detail is as following code :
<code>
def defaultPartitioner(rdd: RDD[_], others: RDD[_]*): Partitioner = {
val bySize = (Seq(rdd) ++ others).sortBy(_.partitions.size).reverse
for (r <- bySize if r.partitioner.isDefined) {
return r.partitioner.get
}
if (rdd.context.conf.contains("spark.default.parallelism")) {
new HashPartitioner(rdd.context.defaultParallelism)
} else {
new HashPartitioner(bySize.head.partitions.size)
}
}
</code>
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/CrazyJvm/spark patch-4
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/403.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #403
----
commit 156833643d9ea1479222e9033164e92a9846351c
Author: Chen Chao <[email protected]>
Date: 2014-04-14T07:39:50Z
misleading task number of groupByKey
"By default, this uses only 8 parallel tasks to do the grouping." is a big
misleading. Please refer to https://github.com/apache/spark/pull/389
detail is as following code :
<code>
def defaultPartitioner(rdd: RDD[_], others: RDD[_]*): Partitioner = {
val bySize = (Seq(rdd) ++ others).sortBy(_.partitions.size).reverse
for (r <- bySize if r.partitioner.isDefined) {
return r.partitioner.get
}
if (rdd.context.conf.contains("spark.default.parallelism")) {
new HashPartitioner(rdd.context.defaultParallelism)
} else {
new HashPartitioner(bySize.head.partitions.size)
}
}
</code>
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