如何在nodejs中监听来自worker的终止信号？

问题描述

我有一个主进程，该主进程使用worker_threads产生了一个新线程。在某些特定情况下，主进程必须关闭该线程，而不必关心它是否已完成其任务，因此MainThread使用terminate()来停止线程。但是，此线程产生了不同的依赖关系，需要在退出之前关闭这些依赖关系。这些依赖项必须从线程中关闭，因此我无法使用worker.on('exit')，因为它在主进程上运行。

是否有某种方法可以监听工作人员本身的终止？

一些我想要实现的最小例子。

const {Worker,isMainThread} = require('worker_threads');

if (isMainThread) {
  const worker = new Worker(__filename);
  worker.on('message',console.log);
  worker.on('error',console.log);
  worker.on('exit',console.log);

  setTimeout(() => {
    console.log('Worker is gonna be terminated');
    worker.terminate();
  },5000);
} else {
  (async () => {
    console.log('I am the worker');
    // This thread will spawn its own dependencies,so I want to listen here the terminate signal from 
    // mainThread to close the dependencies of this worker
    // Sth like the following will be awesome
    // thread.on('exit',() => { /* close dependencies */ })

    // Simulate a task which takes a larger time than MainThread wants to wait
    await new Promise(resolve => {
      setTimeout(resolve,10000);
    });
  })();
}

解决方法

您可以通过 worker.postMessage(value) / parentPort.on("message",(value) => {...}) 向工作线程发出退出信号，然后在工作线程中使用 process.exit()。当然要先清理。

我建议将对象用作 value，这样您就可以将多个命令或日期从主线程传递到工作线程。

const { Worker,isMainThread,parentPort } = require("worker_threads");

if (isMainThread) {
  const worker = new Worker(__filename);
  worker.on("message",console.log);
  worker.on("error",console.log);
  worker.on("exit",console.log);

  setTimeout(() => {
    console.log("Worker is gonna be terminated");
    // replace worker.terminate(); with something like
    worker.postMessage({ exit: true });
    // maybe add another setTimeout with worker.terminate() just in case?
  },5000);
} else {
  (async () => {
    // listen for message and do things according to passed value
    parentPort.on("message",(value) => {
      // worker threads do not have multiple listeners available for passing different event,// therefore add one onMessage listener,and pass an object with commands/data from main thread
      if (value.exit) {
        // clean up
        console.log("doing cleanup");
        process.exit(0);
      }
    });
    // add other logic for receiving messages from main thread

    console.log("I am the worker");
    // This thread will spawn its own dependencies,so I want to listen here the terminate signal from
    // mainThread to close the dependencies of this worker
    // Sth like the following will be awesome
    // thread.on('exit',() => { /* close dependencies */ })

    // Simulate a task which takes a larger time than MainThread wants to wait
    await new Promise((resolve) => {
      setTimeout(resolve,10000);
    });
  })();
}