如何设计具有无限阻塞循环的工作线程顶点？

Question

我正在尝试构建一个worker verticle，通过采用kotlin的PubSub示例，结合这个关于worker无限阻塞循环处理的答案，将Google cloud PubSub主题订阅与vert.x的事件总线连接起来。

它确实有效，但Vert. X在收到来自PubSub的消息后的某个时间通过抛出异常来不断唠叨Thread阻止的日志（请暂时忽略阻止初始化）：

9:15:12 AM: Executing task 'run'...

WARNING: You are a using release candidate 2.0.0-rc5. Behavior of this plugin has changed since 1.3.5. Please see release notes at: https://github.com/GoogleCloudPlatform/app-gradle-plugin.
Missing a feature? Can't get it to work?, please file a bug at: https://github.com/GoogleCloudPlatform/app-gradle-plugin/issues.
:compileKotlin UP-TO-DATE
:compileJava NO-SOURCE
:processResources NO-SOURCE
:classes UP-TO-DATE
Mar 10, 2019 9:15:18 AM io.vertx.core.impl.launcher.commands.Watcher
INFO: Watched paths: [/home/username/IdeaProjects/project_name/./src]
Mar 10, 2019 9:15:18 AM io.vertx.core.impl.launcher.commands.Watcher
INFO: Starting the vert.x application in redeploy mode
:run
Starting vert.x application...
f48ba7fd-a52b-487f-b553-2b74473e58ba-redeploy
Creating topic gcs-project-id:vertx.
Mar 10, 2019 9:15:18 AM com.google.auth.oauth2.DefaultCredentialsProvider warnAboutProblematicCredentials
WARNING: Your application has authenticated using end user credentials from Google Cloud SDK. We recommend that most server applications use service accounts instead. If your application continues to use end user credentials from Cloud SDK, you might receive a "quota exceeded" or "API not enabled" error. For more information about service accounts, see https://cloud.google.com/docs/authentication/.
Mar 10, 2019 9:15:21 AM io.vertx.core.impl.BlockedThreadChecker
WARNING: Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 2759 ms, time limit is 2000 ms
Topic gcs-project-id:vertx successfully created.
Creating subscription gcs-project-id:kotlin.
Mar 10, 2019 9:15:22 AM io.vertx.core.impl.BlockedThreadChecker
WARNING: Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 3759 ms, time limit is 2000 ms
Mar 10, 2019 9:15:23 AM io.vertx.core.impl.BlockedThreadChecker
WARNING: Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 4758 ms, time limit is 2000 ms
Mar 10, 2019 9:15:24 AM io.vertx.core.impl.BlockedThreadChecker
WARNING: Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 5759 ms, time limit is 2000 ms
io.vertx.core.VertxException: Thread blocked
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:469)
    at com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:142)
    at com.google.common.util.concurrent.Futures.getUnchecked(Futures.java:1309)
    at com.google.api.gax.rpc.ApiExceptions.callAndTranslateApiException(ApiExceptions.java:52)
    at com.google.api.gax.rpc.UnaryCallable.call(UnaryCallable.java:112)
    at com.google.cloud.pubsub.v1.SubscriptionAdminClient.createSubscription(SubscriptionAdminClient.java:359)
    at com.google.cloud.pubsub.v1.SubscriptionAdminClient.createSubscription(SubscriptionAdminClient.java:260)
    at com.example.project.MainVerticle.subscribeTopic(MainVerticle.kt:76)
    at com.example.project.MainVerticle.init(MainVerticle.kt:46)
    at io.vertx.core.impl.DeploymentManager.lambda$doDeploy$8(DeploymentManager.java:492)
    at io.vertx.core.impl.DeploymentManager$$Lambda$28/1902260856.handle(Unknown Source)
    at io.vertx.core.impl.ContextImpl.executeTask(ContextImpl.java:320)
    at io.vertx.core.impl.EventLoopContext.lambda$executeAsync$0(EventLoopContext.java:38)
    at io.vertx.core.impl.EventLoopContext$$Lambda$29/1640639994.run(Unknown Source)
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:462)
    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:897)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.lang.Thread.run(Thread.java:748)

Subscription gcs-project-id:kotlin successfully created.
Listening to messages on kotlin:
Mar 10, 2019 9:15:25 AM io.vertx.core.impl.launcher.commands.VertxIsolatedDeployer
INFO: Succeeded in deploying verticle

Message Id: 462746807438186 Data: Bazinga
Message Id: 462746750387788 Data: Another message

Mar 10, 2019 9:16:25 AM io.vertx.core.impl.BlockedThreadChecker
WARNING: Thread Thread[vert.x-worker-thread-0,5,main] has been blocked for 60171 ms, time limit is 60000 ms
io.vertx.core.VertxException: Thread blocked
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingDeque.takeFirst(LinkedBlockingDeque.java:492)
    at java.util.concurrent.LinkedBlockingDeque.take(LinkedBlockingDeque.java:680)
    at com.example.project.MainVerticle$start$1.handle(MainVerticle.kt:32)
    at com.example.project.MainVerticle$start$1.handle(MainVerticle.kt:13)
    at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$2(ContextImpl.java:272)
    at io.vertx.core.impl.ContextImpl$$Lambda$33/1101004004.run(Unknown Source)
    at io.vertx.core.impl.TaskQueue.run(TaskQueue.java:76)
    at io.vertx.core.impl.TaskQueue$$Lambda$26/1213216872.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.lang.Thread.run(Thread.java:748)

Mar 10, 2019 9:16:26 AM io.vertx.core.impl.BlockedThreadChecker
WARNING: Thread Thread[vert.x-worker-thread-0,5,main] has been blocked for 61172 ms, time limit is 60000 ms
io.vertx.core.VertxException: Thread blocked
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingDeque.takeFirst(LinkedBlockingDeque.java:492)
    at java.util.concurrent.LinkedBlockingDeque.take(LinkedBlockingDeque.java:680)
    at com.example.project.MainVerticle$start$1.handle(MainVerticle.kt:32)
    at com.example.project.MainVerticle$start$1.handle(MainVerticle.kt:13)
    at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$2(ContextImpl.java:272)
    at io.vertx.core.impl.ContextImpl$$Lambda$33/1101004004.run(Unknown Source)
    at io.vertx.core.impl.TaskQueue.run(TaskQueue.java:76)
    at io.vertx.core.impl.TaskQueue$$Lambda$26/1213216872.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.lang.Thread.run(Thread.java:748)

这是源代码：

package com.example.project_name

import com.google.api.gax.rpc.ApiException
import com.google.cloud.pubsub.v1.*
import com.google.pubsub.v1.ProjectSubscriptionName
import com.google.pubsub.v1.ProjectTopicName
import com.google.pubsub.v1.PubsubMessage
import com.google.pubsub.v1.PushConfig
import io.vertx.core.*
import java.util.concurrent.LinkedBlockingDeque


class MainVerticle : MessageReceiver, AbstractVerticle() {
  private val projectId = "gcs-project-id"
  private val topicId = "vertx"
  private val topic: ProjectTopicName = ProjectTopicName.of(projectId, topicId)
  private val subscriptionId = "kotlin"
  private val subscription = ProjectSubscriptionName.of(projectId, subscriptionId)
  private val messages = LinkedBlockingDeque<PubsubMessage>()
  private lateinit var subscriber: Subscriber

  override fun receiveMessage(message: PubsubMessage, consumer: AckReplyConsumer) {
    messages.offer(message)
    consumer.ack()
  }

  override fun start() {
    vertx.executeBlocking<Void>({
      try {
        println("Listening to messages on $subscriptionId:")
        subscriber.awaitRunning()
        while (true) {
          val message = messages.take()
          println("Message Id: ${message.messageId} Data: ${message.data.toStringUtf8()}")
        }
      } finally {
        subscriber.stopAsync()
        it.complete()
      }
    }, { println("done, ${it.cause()}") })
  }

  override fun init(vertx: Vertx?, context: Context?) {
    super.init(vertx, context)
    try {
      createTopic()
      subscribeTopic()
      subscriber = Subscriber.newBuilder(subscription, this).build()
      subscriber.startAsync()
    } catch (e: ApiException) {
      // example : code = ALREADY_EXISTS(409) implies topic already exists
      println("Failed: $e")
    }
  }

  override fun stop(stopFuture: Future<Void>?) {
    super.stop(stopFuture)
    try {
      deleteSub()
      deleteTopic()
    } catch (e: ApiException) {
      println("Failed: $e")
    } finally {
      subscriber.stopAsync()
      stopFuture!!.complete()
    }
  }

  private fun createTopic() { // expects 1 arg: <topic> to create
    println("Creating topic ${topic.project}:${topic.topic}.")
    TopicAdminClient.create().use { topicAdminClient -> topicAdminClient.createTopic(topic) }
    println("Topic ${topic.project}:${topic.topic} successfully created.")
  }

  private fun subscribeTopic() { // expects 2 args: <topic> and <subscription>
    println("Creating subscription ${subscription.project}:${subscription.subscription}.")
    SubscriptionAdminClient.create().use { it.createSubscription(subscription, topic, PushConfig.getDefaultInstance(), 0) }
    println("Subscription ${subscription.project}:${subscription.subscription} successfully created.")
  }

  private fun deleteTopic() {
    println("Deleting topic ${topic.project}:${topic.topic}.")
    TopicAdminClient.create().use { it.deleteTopic(topic) }
    println("Topic ${topic.project}:${topic.topic} successfully deleted.")
  }

  private fun deleteSub() { // expects 1 arg: <subscription> to delete
    println("Deleting subscription ${subscription.project}:${subscription.subscription}.")
    SubscriptionAdminClient.create().use { it.deleteSubscription(subscription) }
    println("Subscription ${subscription.project}:${subscription.subscription} successfully deleted.")
  }
}

fun main(vararg args: String) {
  Vertx.vertx().deployVerticle(MainVerticle(), DeploymentOptions().apply {
    isWorker = true
  })
}

我显然错过了一些东西。此外，如果您有更好的方法可以将Google的PubSub库（具有自己的异步循环）与Vert.X集成/统一，我很乐意听到我的原始示例方法。

Answer 1

问题出在您的 while 循环上。

在这种情况下，“阻塞”并不意味着你可以永远保持运行。您对的调用。complete（）从未达到，并且在某一点上达到Vert。x会抱怨这一点。

请参阅有关运行阻止代码的手册，特别是“警告”部分。

为了解决您的问题，您需要以一种或另一种方式安排对messages.take（）的调用，例如使用set周期。在间隔处理程序中，使用执行阻止清空队列，然后通过调用完成（）来返回控制权，无论是在您安排消息处理之前还是之后，这取决于您是否关心结果。