Github user mccheah commented on a diff in the pull request:
https://github.com/apache/spark/pull/21366#discussion_r194184310
--- Diff:
resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsSnapshotsStoreImpl.scala
---
@@ -0,0 +1,95 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.scheduler.cluster.k8s
+
+import java.util.concurrent.{ExecutorService, ScheduledExecutorService,
TimeUnit}
+
+import com.google.common.collect.Lists
+import io.fabric8.kubernetes.api.model.Pod
+import io.reactivex.disposables.Disposable
+import io.reactivex.functions.Consumer
+import io.reactivex.schedulers.Schedulers
+import io.reactivex.subjects.PublishSubject
+import javax.annotation.concurrent.GuardedBy
+import scala.collection.JavaConverters._
+import scala.collection.mutable
+
+import org.apache.spark.util.{ThreadUtils, Utils}
+
+private[spark] class ExecutorPodsSnapshotsStoreImpl(
+ bufferSnapshotsExecutor: ScheduledExecutorService,
+ executeSubscriptionsExecutor: ExecutorService)
+ extends ExecutorPodsSnapshotsStore {
+
+ private val SNAPSHOT_LOCK = new Object()
+
+ private val snapshotsObservable =
PublishSubject.create[ExecutorPodsSnapshot]()
+ private val observedDisposables = mutable.Buffer.empty[Disposable]
+
+ @GuardedBy("SNAPSHOT_LOCK")
+ private var currentSnapshot = ExecutorPodsSnapshot()
+
+ override def addSubscriber(
+ processBatchIntervalMillis: Long)
+ (subscriber: ExecutorPodsSnapshot => Unit): Unit = {
+ observedDisposables += snapshotsObservable
+ // Group events in the time window given by the caller. These
buffers are then sent
+ // to the caller's lambda at the given interval, with the pod
updates that occurred
+ // in that given interval.
+ .buffer(
+ processBatchIntervalMillis,
+ TimeUnit.MILLISECONDS,
+ // For testing - specifically use the given scheduled executor
service to trigger
+ // buffer boundaries. Allows us to inject a deterministic
scheduler here.
+ Schedulers.from(bufferSnapshotsExecutor))
+ // Trigger an event cycle immediately. Not strictly required to be
fully correct, but
+ // in particular the pod allocator should try to request executors
immediately instead
+ // of waiting for one pod allocation delay.
+ .startWith(Lists.newArrayList(ExecutorPodsSnapshot()))
+ // Force all triggered events - both the initial event above and the
buffered ones in
+ // the following time windows - to execute asynchronously to this
call's thread.
+ .observeOn(Schedulers.from(executeSubscriptionsExecutor))
+ .subscribe(toReactivexConsumer { snapshots:
java.util.List[ExecutorPodsSnapshot] =>
+ Utils.tryLogNonFatalError {
+ snapshots.asScala.foreach(subscriber)
+ }
+ })
+ }
+
+ override def stop(): Unit = {
+ observedDisposables.foreach(_.dispose())
+ snapshotsObservable.onComplete()
+ ThreadUtils.shutdown(bufferSnapshotsExecutor)
+ ThreadUtils.shutdown(executeSubscriptionsExecutor)
+ }
+
+ override def updatePod(updatedPod: Pod): Unit =
SNAPSHOT_LOCK.synchronized {
+ currentSnapshot = currentSnapshot.withUpdate(updatedPod)
--- End diff --
A brief remark that one still might not be 100% accurate because of
failures in the information flow (missing events etc) - but for all the events
we do get we should be trying to handle them all as best we can.
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