worker_thread #

//基于worker_threads开启多线程工作
    this._worker = new Worker(path.resolve(__dirname, './threadChild.js'), {
      eval: false,
      stderr: true,
      stdout: true,
      workerData: {
        cwd: process.cwd(),
        env: {
          ...process.env,
          JEST_WORKER_ID: String(this._options.workerId + 1), // 0-indexed workerId, 1-indexed JEST_WORKER_ID
        } as NodeJS.ProcessEnv,
        // Suppress --debug / --inspect flags while preserving others (like --harmony).
        execArgv: process.execArgv.filter(v => !/^--(debug|inspect)/.test(v)),
        silent: true,
        ...this._options.forkOptions,
      },
    });

    if (this._worker.stdout) {
      if (!this._stdout) {
        // We need to add a permanent stream to the merged stream to prevent it
        // from ending when the subprocess stream ends
        this._stdout = mergeStream(this._getFakeStream());
      }

      this._stdout.add(this._worker.stdout);
    }

    if (this._worker.stderr) {
      if (!this._stderr) {
        // We need to add a permanent stream to the merged stream to prevent it
        // from ending when the subprocess stream ends
        this._stderr = mergeStream(this._getFakeStream());
      }

      this._stderr.add(this._worker.stderr);
    }

    this._worker.on('message', this.onMessage.bind(this));
    this._worker.on('exit', this.onExit.bind(this));

    this._worker.postMessage([
      CHILD_MESSAGE_INITIALIZE,
      false,
      this._options.workerPath,
      this._options.setupArgs,
    ]);

import {parentPort, isMainThread} from 'worker_threads';

parentPort!.on('message', (request: any) => {
  switch (request[0]) {
    case CHILD_MESSAGE_INITIALIZE:
      const init: ChildMessageInitialize = request;
      file = init[2];
      setupArgs = request[3];
      break;

    case CHILD_MESSAGE_CALL:
      const call: ChildMessageCall = request;
      execMethod(call[2], call[3]);
      break;

    case CHILD_MESSAGE_END:
      end();
      break;

    default:
      throw new TypeError(
        'Unexpected request from parent process: ' + request[0],
      );
  }
});