Github user mateiz commented on a diff in the pull request:
https://github.com/apache/spark/pull/1313#discussion_r15508212
--- Diff:
core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala ---
@@ -246,28 +246,36 @@ private[spark] class TaskSchedulerImpl(
// Take each TaskSet in our scheduling order, and then offer it each
node in increasing order
// of locality levels so that it gets a chance to launch local tasks
on all of them.
+ // NOTE: the preferredLocality order: PROCESS_LOCAL, NODE_LOCAL,
NOPREF, RACK_local, ANY
var launchedTask = false
- for (taskSet <- sortedTaskSets; maxLocality <-
taskSet.myLocalityLevels) {
- do {
- launchedTask = false
- for (i <- 0 until shuffledOffers.size) {
- val execId = shuffledOffers(i).executorId
- val host = shuffledOffers(i).host
- if (availableCpus(i) >= CPUS_PER_TASK) {
- for (task <- taskSet.resourceOffer(execId, host, maxLocality))
{
- tasks(i) += task
- val tid = task.taskId
- taskIdToTaskSetId(tid) = taskSet.taskSet.id
- taskIdToExecutorId(tid) = execId
- activeExecutorIds += execId
- executorsByHost(host) += execId
- availableCpus(i) -= CPUS_PER_TASK
- assert (availableCpus(i) >= 0)
- launchedTask = true
+ for (taskSet <- sortedTaskSets; preferredLocality <-
taskSet.myLocalityLevels) {
+ def launchTaskOnLocalityLevel(locality: TaskLocality.Value) {
+ do {
+ launchedTask = false
+ for (i <- 0 until shuffledOffers.size) {
+ val execId = shuffledOffers(i).executorId
+ val host = shuffledOffers(i).host
+ if (availableCpus(i) >= CPUS_PER_TASK) {
+ for (task <- taskSet.resourceOffer(execId, host, locality)) {
+ tasks(i) += task
+ val tid = task.taskId
+ taskIdToTaskSetId(tid) = taskSet.taskSet.id
+ taskIdToExecutorId(tid) = execId
+ activeExecutorIds += execId
+ executorsByHost(host) += execId
+ availableCpus(i) -= CPUS_PER_TASK
+ assert(availableCpus(i) >= 0)
+ launchedTask = true
+ }
}
}
- }
- } while (launchedTask)
+ } while (launchedTask)
+ }
+ launchTaskOnLocalityLevel(preferredLocality)
+ // search noPref task after we have launched all node_local and
nearer tasks
+ if (preferredLocality == TaskLocality.NODE_LOCAL) {
+ launchTaskOnLocalityLevel(TaskLocality.NOPREF)
+ }
--- End diff --
Instead of modifying the code here, make taskSet.myLocalityLevels include
NO_PREFS in its list if it has tasks with no preferences. IMO that makes this
logic even simpler.
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