Spark source code: new stage in DAGScheduler
I am reading the source code of DAGScheduler from Spark's 0.5 branch.
The newStage method:
def newStage(rdd: RDD[_], shuffleDep: Option[ShuffleDependency[_,_,_]]): Stage = {
cacheTracker.registerRDD(rdd.id, rdd.splits.size)
...
val id = nextStageId.getAndIncrement()
val stage = new Stage(id, rdd, shuffleDep, getParentStages(rdd))
...
}
Firstly, it calls registerRDD to register the rdd, and is actually stored as a Hashset.
Secondly, it crates a new Stage.
Inside the getParentStages, it will return the parents dependencies of the rdd, but it will also always register this rdd again in addition to its parents.
The basic logic (pseudocode) of getParentStages is:
def visit(rdd) {
if (rdd not visited) {
set rdd visited;
registerRDD(rdd);
for (each dep in rdd.dependencies) {
visit(dep.rdd)
}
}
}
visit(rdd)
In my view, since this rdd will be registered in getParentStages anyway, is it necessary to register it in newStage method?
Of course, since the underlying data structure is a HashSet, nothing will happen when registering again.
scala apache-spark
asked Nov 23 at 7:35
chenzhongpu
2,24232451
add a comment |
I am reading the source code of DAGScheduler from Spark's 0.5 branch.
The newStage method:
def newStage(rdd: RDD[_], shuffleDep: Option[ShuffleDependency[_,_,_]]): Stage = {
cacheTracker.registerRDD(rdd.id, rdd.splits.size)
...
val id = nextStageId.getAndIncrement()
val stage = new Stage(id, rdd, shuffleDep, getParentStages(rdd))
...
}
Firstly, it calls registerRDD to register the rdd, and is actually stored as a Hashset.
Secondly, it crates a new Stage.
Inside the getParentStages, it will return the parents dependencies of the rdd, but it will also always register this rdd again in addition to its parents.
The basic logic (pseudocode) of getParentStages is:
def visit(rdd) {
if (rdd not visited) {
set rdd visited;
registerRDD(rdd);
for (each dep in rdd.dependencies) {
visit(dep.rdd)
}
}
}
visit(rdd)
In my view, since this rdd will be registered in getParentStages anyway, is it necessary to register it in newStage method?
Of course, since the underlying data structure is a HashSet, nothing will happen when registering again.
scala apache-spark
asked Nov 23 at 7:35
chenzhongpu
2,24232451
add a comment |
I am reading the source code of DAGScheduler from Spark's 0.5 branch.
The newStage method:
def newStage(rdd: RDD[_], shuffleDep: Option[ShuffleDependency[_,_,_]]): Stage = {
cacheTracker.registerRDD(rdd.id, rdd.splits.size)
...
val id = nextStageId.getAndIncrement()
val stage = new Stage(id, rdd, shuffleDep, getParentStages(rdd))
...
}
Firstly, it calls registerRDD to register the rdd, and is actually stored as a Hashset.
Secondly, it crates a new Stage.
Inside the getParentStages, it will return the parents dependencies of the rdd, but it will also always register this rdd again in addition to its parents.
The basic logic (pseudocode) of getParentStages is:
def visit(rdd) {
if (rdd not visited) {
set rdd visited;
registerRDD(rdd);
for (each dep in rdd.dependencies) {
visit(dep.rdd)
}
}
}
visit(rdd)
In my view, since this rdd will be registered in getParentStages anyway, is it necessary to register it in newStage method?
Of course, since the underlying data structure is a HashSet, nothing will happen when registering again.
scala apache-spark
asked Nov 23 at 7:35
chenzhongpu
2,24232451
I am reading the source code of DAGScheduler from Spark's 0.5 branch.
The newStage method:
def newStage(rdd: RDD[_], shuffleDep: Option[ShuffleDependency[_,_,_]]): Stage = {
cacheTracker.registerRDD(rdd.id, rdd.splits.size)
...
val id = nextStageId.getAndIncrement()
val stage = new Stage(id, rdd, shuffleDep, getParentStages(rdd))
...
}
Firstly, it calls registerRDD to register the rdd, and is actually stored as a Hashset.
Secondly, it crates a new Stage.
Inside the getParentStages, it will return the parents dependencies of the rdd, but it will also always register this rdd again in addition to its parents.
The basic logic (pseudocode) of getParentStages is:
def visit(rdd) {
if (rdd not visited) {
set rdd visited;
registerRDD(rdd);
for (each dep in rdd.dependencies) {
visit(dep.rdd)
}
}
}
visit(rdd)
In my view, since this rdd will be registered in getParentStages anyway, is it necessary to register it in newStage method?
Of course, since the underlying data structure is a HashSet, nothing will happen when registering again.
scala apache-spark
scala apache-spark
asked Nov 23 at 7:35
chenzhongpu
2,24232451
asked Nov 23 at 7:35
chenzhongpu
2,24232451
edited Nov 23 at 7:51
asked Nov 23 at 7:35
chenzhongpu
2,24232451
asked Nov 23 at 7:35
chenzhongpu
2,24232451
asked Nov 23 at 7:35
chenzhongpu
2,24232451
2,24232451
add a comment |
add a comment |
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