feat: Add support for virtualize fork join pool

actor-tests/src/test/scala-jdk21-only/org/apache/pekko/dispatch/ForkJoinPoolVirtualzedSpec.scala

@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * license agreements; and to You under the Apache License, version 2.0:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * This file is part of the Apache Pekko project, which was derived from Akka.
+ */
+
+/*
+ * Copyright (C) 2018-2022 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package org.apache.pekko.dispatch
+
+import com.typesafe.config.ConfigFactory
+
+import org.apache.pekko
+import pekko.actor.{ Actor, Props }
+import pekko.testkit.{ ImplicitSender, PekkoSpec }
+import pekko.util.JavaVersion
+
+object ForkJoinPoolVirtualzedSpec {
+  val config = ConfigFactory.parseString("""
+      |virtual {
+      |  task-dispatcher {
+      |    mailbox-type = "org.apache.pekko.dispatch.SingleConsumerOnlyUnboundedMailbox"
+      |    throughput = 5
+      |    fork-join-executor {
+      |      parallelism-factor = 2
+      |      parallelism-max = 2
+      |      parallelism-min = 2
+      |      virtualize = on
+      |    }
+      |  }
+      |}
+    """.stripMargin)
+
+  class ThreadNameActor extends Actor {
+
+    override def receive = {
+      case "ping" =>
+        sender() ! Thread.currentThread().getName
+    }
+  }
+
+}
+
+class ForkJoinPoolVirtualzedSpec extends PekkoSpec(ForkJoinPoolVirtualzedSpec.config) with ImplicitSender {
+  import ForkJoinPoolVirtualzedSpec._
+
+  "PekkoForkJoinPool" must {
+
+    "support virtualization with Virtual Thread" in {
+      val actor = system.actorOf(Props(new ThreadNameActor).withDispatcher("virtual.task-dispatcher"))
+
+      for (_ <- 1 to Iterations) {
+        // External task submission via the default dispatcher
+        actor ! "ping"
+        expectMsgPF() { case name: String => name should contains("virtual-thread") }
+      }
+    }
+
+  }
+}

actor-tests/src/test/scala-jdk21-only/org/apache/pekko/dispatch/VirtualThreadPoolDispatcherSpec.scala

@@ -43,8 +43,6 @@ object VirtualThreadPoolDispatcherSpec {
 class VirtualThreadPoolDispatcherSpec extends PekkoSpec(VirtualThreadPoolDispatcherSpec.config) with ImplicitSender {
   import VirtualThreadPoolDispatcherSpec._
 
-  val Iterations = 1000
-
   "VirtualThreadPool support" must {
 
     "handle simple dispatch" in {

actor/src/main/resources/reference.conf

@@ -487,6 +487,11 @@ pekko {
         # This config is new in Pekko v1.1.0 and only has an effect if you are running with JDK 9 and above.
         # Read the documentation on `java.util.concurrent.ForkJoinPool` to find out more. Default in hex is 0x7fff.
         maximum-pool-size = 32767
+
+        # This config is new in Pekko v1.2.0 and only has an effect if you are running with JDK 21 and above.
+        # Virtualize this dispatcher as a virtual-thread-executor
+        # Valid values are: `on`, `off`
+        virtualize = off
       }
 
       # This will be used if you have set "executor = "thread-pool-executor""

actor/src/main/scala/org/apache/pekko/dispatch/ForkJoinExecutorConfigurator.scala

@@ -89,12 +89,18 @@ class ForkJoinExecutorConfigurator(config: Config, prerequisites: DispatcherPrer
       val threadFactory: ForkJoinPool.ForkJoinWorkerThreadFactory,
       val parallelism: Int,
       val asyncMode: Boolean,
-      val maxPoolSize: Int)
+      val maxPoolSize: Int,
+      val virtualize: Boolean)
       extends ExecutorServiceFactory {
 
     def this(threadFactory: ForkJoinPool.ForkJoinWorkerThreadFactory,
         parallelism: Int,
-        asyncMode: Boolean) = this(threadFactory, parallelism, asyncMode, ForkJoinPoolConstants.MaxCap)
+        asyncMode: Boolean) = this(threadFactory, parallelism, asyncMode, ForkJoinPoolConstants.MaxCap, false)
+
+    def this(threadFactory: ForkJoinPool.ForkJoinWorkerThreadFactory,
+        parallelism: Int,
+        asyncMode: Boolean,
+        maxPoolSize: Int) = this(threadFactory, parallelism, asyncMode, maxPoolSize, false)
 
     private def pekkoJdk9ForkJoinPoolClassOpt: Option[Class[_]] =
       Try(Class.forName("org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool")).toOption
@@ -116,12 +122,19 @@ class ForkJoinExecutorConfigurator(config: Config, prerequisites: DispatcherPrer
     def this(threadFactory: ForkJoinPool.ForkJoinWorkerThreadFactory, parallelism: Int) =
       this(threadFactory, parallelism, asyncMode = true)
 
-    def createExecutorService: ExecutorService = pekkoJdk9ForkJoinPoolHandleOpt match {
-      case Some(handle) =>
-        handle.invoke(parallelism, threadFactory, maxPoolSize,
-          MonitorableThreadFactory.doNothing, asyncMode).asInstanceOf[ExecutorService]
-      case _ =>
-        new PekkoForkJoinPool(parallelism, threadFactory, MonitorableThreadFactory.doNothing, asyncMode)
+    def createExecutorService: ExecutorService = {
+      val forkJoinPool = pekkoJdk9ForkJoinPoolHandleOpt match {
+        case Some(handle) =>
+          handle.invoke(parallelism, threadFactory, maxPoolSize,
+            MonitorableThreadFactory.doNothing, asyncMode).asInstanceOf[ExecutorService]
+        case _ =>
+          new PekkoForkJoinPool(parallelism, threadFactory, MonitorableThreadFactory.doNothing, asyncMode)
+      }
+      if (virtualize) {
+        new VirtualizedExecutorService("pekko", forkJoinPool)
+      } else {
+        forkJoinPool
+      }
     }
   }
 
@@ -149,6 +162,7 @@ class ForkJoinExecutorConfigurator(config: Config, prerequisites: DispatcherPrer
         config.getDouble("parallelism-factor"),
         config.getInt("parallelism-max")),
       asyncMode,
-      config.getInt("maximum-pool-size"))
+      config.getInt("maximum-pool-size"),
+      config.getBoolean("virtualize"))
   }
 }

actor/src/main/scala/org/apache/pekko/dispatch/ThreadPoolBuilder.scala

@@ -64,6 +64,10 @@ object ThreadPoolConfig {
  * Function0 without the fun stuff (mostly for the sake of the Java API side of things)
  */
 trait ExecutorServiceFactory {
+
+  /**
+   * Create a new ExecutorService
+   */
   def createExecutorService: ExecutorService
 }
 

actor/src/main/scala/org/apache/pekko/dispatch/VirtualizedExecutorService.scala

@@ -0,0 +1,89 @@
+/*
+ * 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.pekko.dispatch
+
+import org.apache.pekko.annotation.InternalApi
+
+import java.util
+import java.util.concurrent.{ Callable, ExecutorService, Future, TimeUnit }
+
+/**
+ * A virtualized executor service that creates a new virtual thread for each task.
+ * Will shut down the underlying executor service when this executor is being shutdown.
+ *
+ * INTERNAL API
+ */
+@InternalApi
+final class VirtualizedExecutorService(prefix: String, underlying: ExecutorService) extends ExecutorService {
+  private val executor = VirtualThreadSupport.newThreadPerTaskExecutor(prefix, underlying)
+
+  override def shutdown(): Unit = {
+    executor.shutdown()
+    underlying.shutdown()
+  }
+
+  override def shutdownNow(): util.List[Runnable] = {
+    executor.shutdownNow()
+    underlying.shutdownNow()
+  }
+
+  override def isShutdown: Boolean = {
+    executor.isShutdown || underlying.isShutdown
+  }
+
+  override def isTerminated: Boolean = {
+    executor.isTerminated && underlying.isTerminated
+  }
+
+  override def awaitTermination(timeout: Long, unit: TimeUnit): Boolean = {
+    executor.awaitTermination(timeout, unit) && underlying.awaitTermination(timeout, unit)
+  }
+
+  override def submit[T](task: Callable[T]): Future[T] = {
+    executor.submit(task)
+  }
+
+  override def submit[T](task: Runnable, result: T): Future[T] = {
+    executor.submit(task, result)
+  }
+
+  override def submit(task: Runnable): Future[_] = {
+    executor.submit(task)
+  }
+
+  override def invokeAll[T](tasks: util.Collection[_ <: Callable[T]]): util.List[Future[T]] = {
+    executor.invokeAll(tasks)
+  }
+
+  override def invokeAll[T](
+      tasks: util.Collection[_ <: Callable[T]], timeout: Long, unit: TimeUnit): util.List[Future[T]] = {
+    executor.invokeAll(tasks, timeout, unit)
+  }
+
+  override def invokeAny[T](tasks: util.Collection[_ <: Callable[T]]): T = {
+    executor.invokeAny(tasks)
+  }
+
+  override def invokeAny[T](tasks: util.Collection[_ <: Callable[T]], timeout: Long, unit: TimeUnit): T = {
+    executor.invokeAny(tasks, timeout, unit)
+  }
+
+  override def execute(command: Runnable): Unit = {
+    executor.execute(command)
+  }
+}