child process doesn't exit

Question

Following is my gulp task:

    httpServer.on("close", (code, signal) => {
      console.log(
        `child process terminated due to receipt of signal ${signal}, code ${code}`
      );
      console.log("httpServer close");
      resolve();
    })
  );
  await new Promise((resolve) => setTimeout(resolve, 2e3));
  httpServer.kill("SIGINT");
  await httpServerClose;
  console.log("here");

I got following output:

Available on:
  http://127.0.0.1:5001
  http://192.168.31.122:5001
  http://172.21.96.1:5001
  http://172.18.192.1:5001
Hit CTRL-C to stop the server

child process terminated due to receipt of signal SIGINT, code null
httpServer close
here

[13:32:57] Finished 'build:release' after 2.01 s

The problem is port 5001 is still in use. I'm on windows 10, node v16.13.1

Answer 1

.kill() doesn't guarantees that the process will successfully terminate. You may check for the resulting boolean that kill() returns, but that only indicates wheter the signal was delivered or not.

childProcess.on('close', (code, signal) => {
  console.log(
    `child process terminated due to receipt of signal ${signal}`);
});

// Send SIGHUP to process.
const signalDelivered = childProcess.kill('SIGHUP');
console.log(signalDelivered)

For some reason, the childProcess is still running / crashed or the SIGINT was not handled correctly. My suggestion is that you implement "Graceful shutdown".

Remember, if in your childProcess code you are handling process.on('SIGINT', ..),you need to close the server that is listening connections and then call process.exit(0).

const server = app.listen(5001)
process.on('SIGINT',function(){
  server.close(err => {
    //exit after server is not listening anymore
    process.exit(err ? 1 : 0)
  })
});