Ngone51 commented on a change in pull request #29211:
URL: https://github.com/apache/spark/pull/29211#discussion_r466251813
##########
File path:
core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala
##########
@@ -442,6 +442,16 @@ class CoarseGrainedSchedulerBackend(scheduler:
TaskSchedulerImpl, val rpcEnv: Rp
case e: Exception =>
logError(s"Unexpected error during decommissioning ${e.toString}",
e)
}
+ // Send decommission message to the executor, this may be a duplicate
since the executor
Review comment:
So we need to prevent duplicate `DecommissionSelf` at the executor side?
For now, I don't see we handle duplicate `DecommissionSelf` and it may create
duplicate threads as a result.
##########
File path:
core/src/main/scala/org/apache/spark/executor/CoarseGrainedExecutorBackend.scala
##########
@@ -277,12 +282,59 @@ private[spark] class CoarseGrainedExecutorBackend(
if (executor != null) {
executor.decommission()
}
- logInfo("Done decommissioning self.")
+ // Shutdown the executor once all tasks are gone & any configured
migrations completed.
+ // Detecting migrations completion doesn't need to be perfect and we
want to minimize the
+ // overhead for executors that are not in decommissioning state as
overall that will be
+ // more of the executors. For example, this will not catch a block which
is already in
+ // the process of being put from a remote executor before migration
starts. This trade-off
+ // is viewed as acceptable to minimize introduction of any new locking
structures in critical
+ // code paths.
+
+ val shutdownThread = new Thread("wait-for-blocks-to-migrate") {
+ override def run(): Unit = {
+ var lastTaskRunningTime = System.nanoTime()
+ val sleep_time = 1000 // 1s
+
+ while (true) {
+ logInfo("Checking to see if we can shutdown.")
+ Thread.sleep(sleep_time)
+ if (executor == null || executor.numRunningTasks == 0) {
+ if (env.conf.get(STORAGE_DECOMMISSION_ENABLED)) {
+ logInfo("No running tasks, checking migrations")
+ val (migrationTime, allBlocksMigrated) =
env.blockManager.lastMigrationInfo()
+ // We can only trust allBlocksMigrated boolean value if there
were no tasks running
+ // since the start of computing it.
+ if (allBlocksMigrated && (migrationTime >
lastTaskRunningTime)) {
+ logInfo("No running tasks, all blocks migrated, stopping.")
+ exitExecutor(0, "Finished decommissioning", notifyDriver =
true)
+ } else {
+ logInfo("All blocks not yet migrated.")
+ }
+ } else {
+ logInfo("No running tasks, no block migration configured,
stopping.")
+ exitExecutor(0, "Finished decommissioning", notifyDriver =
true)
Review comment:
I'm wondering if we need to wait for tasks to finish if storage
decommission is disabled. I mean, for a shuffle map task and result task with
indirect result, their outputs still base on blocks. As a result, we'd spend
time waiting for them to finish but get nothing good in return.
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