vanzin commented on a change in pull request #26059: [SPARK-29398][core] Support dedicated thread pools for RPC endpoints. URL: https://github.com/apache/spark/pull/26059#discussion_r336084617
########## File path: core/src/main/scala/org/apache/spark/rpc/netty/MessageLoop.scala ########## @@ -0,0 +1,194 @@ +/* + * 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.rpc.netty + +import java.util.concurrent._ + +import scala.util.control.NonFatal + +import org.apache.spark.{SparkConf, SparkContext} +import org.apache.spark.internal.Logging +import org.apache.spark.internal.config.EXECUTOR_ID +import org.apache.spark.internal.config.Network._ +import org.apache.spark.rpc.{IsolatedRpcEndpoint, RpcEndpoint} +import org.apache.spark.util.ThreadUtils + +/** + * A message loop used by [[Dispatcher]] to deliver messages to endpoints. + */ +private sealed abstract class MessageLoop(dispatcher: Dispatcher) extends Logging { + + // List of inboxes with pending messages, to be processed by the message loop. + private val active = new LinkedBlockingQueue[Inbox]() + + // Message loop task; should be run in all threads of the message loop's pool. + protected val receiveLoopRunnable = new Runnable() { + override def run(): Unit = receiveLoop() + } + + protected val threadpool: ExecutorService + + private var stopped = false + + def post(endpointName: String, message: InboxMessage): Unit + + def unregister(name: String): Unit + + def stop(): Unit = { + synchronized { + if (!stopped) { + setActive(MessageLoop.PoisonPill) + threadpool.shutdown() + stopped = true + } + } + threadpool.awaitTermination(Long.MaxValue, TimeUnit.MILLISECONDS) + } + + protected final def setActive(inbox: Inbox): Unit = active.offer(inbox) + + private def receiveLoop(): Unit = { + try { + while (true) { + try { + val inbox = active.take() + if (inbox == MessageLoop.PoisonPill) { + // Put PoisonPill back so that other threads can see it. + setActive(MessageLoop.PoisonPill) + return + } + inbox.process(dispatcher) + } catch { + case NonFatal(e) => logError(e.getMessage, e) + } + } + } catch { + case _: InterruptedException => // exit + case t: Throwable => + try { + // Re-submit a receive task so that message delivery will still work if + // UncaughtExceptionHandler decides to not kill JVM. + threadpool.execute(receiveLoopRunnable) + } finally { + throw t + } + } + } +} + +private object MessageLoop { + /** A poison inbox that indicates the message loop should stop processing messages. */ + val PoisonPill = new Inbox(null, null) +} + +/** + * A message loop that serves multiple RPC endpoints, using a shared thread pool. + */ +private class SharedMessageLoop( + conf: SparkConf, + dispatcher: Dispatcher, + numUsableCores: Int) + extends MessageLoop(dispatcher) { + + private val endpoints = new ConcurrentHashMap[String, Inbox]() + + private def getNumOfThreads(conf: SparkConf): Int = { + val availableCores = + if (numUsableCores > 0) numUsableCores else Runtime.getRuntime.availableProcessors() + + val modNumThreads = conf.get(RPC_NETTY_DISPATCHER_NUM_THREADS) + .getOrElse(math.max(2, availableCores)) + + conf.get(EXECUTOR_ID).map { id => + val role = if (id == SparkContext.DRIVER_IDENTIFIER) "driver" else "executor" + conf.getInt(s"spark.$role.rpc.netty.dispatcher.numThreads", modNumThreads) + }.getOrElse(modNumThreads) + } + + /** Thread pool used for dispatching messages. */ + override protected val threadpool: ThreadPoolExecutor = { + val numThreads = getNumOfThreads(conf) + val pool = ThreadUtils.newDaemonFixedThreadPool(numThreads, "dispatcher-event-loop") + for (i <- 0 until numThreads) { + pool.execute(receiveLoopRunnable) + } + pool + } + + override def post(endpointName: String, message: InboxMessage): Unit = { + val inbox = endpoints.get(endpointName) + inbox.post(message) + setActive(inbox) + } + + override def unregister(name: String): Unit = { + val inbox = endpoints.remove(name) + if (inbox != null) { + inbox.stop() + // Mark active to handle the OnStop message. + setActive(inbox) + } + } + + def register(name: String, endpoint: RpcEndpoint): Unit = { + val inbox = new Inbox(name, endpoint) + endpoints.put(name, inbox) + // Mark active to handle the OnStart message. + setActive(inbox) + } +} + +/** + * A message loop that is dedicated to a single RPC endpoint. + */ +private class DedicatedMessageLoop( + name: String, + endpoint: IsolatedRpcEndpoint, + dispatcher: Dispatcher) + extends MessageLoop(dispatcher) { + + private val inbox = new Inbox(name, endpoint) + + override protected val threadpool = if (endpoint.threadCount() > 1) { + ThreadUtils.newDaemonCachedThreadPool(s"dispatcher-$name", endpoint.threadCount()) + } else { + ThreadUtils.newDaemonSingleThreadExecutor(s"dispatcher-$name") + } + + (1 to endpoint.threadCount()).foreach { _ => + threadpool.submit(receiveLoopRunnable) + } + + // Mark active to handle the OnStart message. + setActive(inbox) + + override def post(endpointName: String, message: InboxMessage): Unit = { + require(endpointName == name) + inbox.post(message) + setActive(inbox) + } + + override def unregister(endpointName: String): Unit = synchronized { Review comment: `Dispatcher` makes sure only to call this once. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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