After calling setupHistory, the program continues to run even after the REPL is closed.

[LiST-GIT]

Version

v20.5.0

Platform

macos

Subsystem

No response

What steps will reproduce the bug?

const repl = require('repl');

var r = repl.start({});
r.setupHistory(__dirname + '/history', () => { }); // Different results will occur here
r.close();

How often does it reproduce? Is there a required condition?

No response

What is the expected behavior? Why is that the expected behavior?

No response

What do you see instead?

After calling setupHistory, the program continues to run even after the REPL is closed.

Additional information

No response

[lucshi]

Hi @LiST-GIT, according to the document, the rl.close() method closes the Interface instance and relinquishes control over the input and output streams. When called, the 'close' event will be emitted. Calling rl.close() does not immediately stop other events (including 'line') from being emitted by the Interface instance. IMO, rl.close() does not exit the process.

In the test code, var r = repl.start({}); opens stdin and stdout and wait for users input so closing the REPL server does not exit the stdin and stdout unless users send EXIT event.

I wrote 2 samples to make the test code work smoothly:

const repl = require('repl');
const path = require('path');

// Start the REPL session
const r = repl.start();


r.setupHistory(path.join(__dirname, '/history'), () => {});

r.close();

r.on('exit', () => {
    console.log('REPL session closed.');
    process.exit();
  });

It quits the node process very soon without giving users chance to input and save into history.
Below modifications let users input and save history and exit by inputing ".exit" in the repl.

const repl = require('repl');
const path = require('path');

// Start the REPL session
const r = repl.start({
  prompt: '> '  
});

// Setup the history for the REPL session
r.setupHistory(path.join(__dirname, '/history'), (err) => {
  if (err) {
    console.log('Error setting up history:', err);
  } else {
    console.log('History setup completed.');
  }
});

// Define the exit event handling
r.on('exit', () => {
  console.log('REPL session closed.');
  process.exit();
});

[lucshi]

If agreed, would I submit a PR to explain the repl.close() behavior more clearly especially for stdin and stdou cases instead of file stream cases?

[LiST-GIT]

Thank you for your response @lucshi . I've updated the code again. In the callback of setupHistory, calling r.pause can now properly exit the program. I think it might be because r.close already calls r.pause, but in setupHistory, due to the asynchronous fd executing the open callback, r.resume is called again, which is why it continues to wait on stdin. Is this by design?

const repl = require('repl');

var r = repl.start({});
r.setupHistory(__dirname + '/history', () => {
    r.pause();
});
r.close();

[lucshi]

According to the REPL implementation , setupHistory resumes the REPL again even if it has been closed. IMHO, in real pracise, users (programmers) ought to know the callback of setupHistory occurs after r.close() so the original code snippet does not make great sense although it is a great corner test case. Usually users are supposed to do some evaluations to well use REPL after history setup. A common code snippet found on web be like :

const repl = require('repl');
const fs = require('fs');

// Start the REPL
const myRepl = repl.start({
  prompt: '> '
});

// Setup history file
const historyFilePath = __dirname + '/history.txt';
myRepl.setupHistory(historyFilePath, () => {
  console.log('History setup complete.');

  // Execute some commands after history setup
  myRepl.eval('console.log("Executing command 1")', myRepl.context, 'history_callback', (err, result) => {
    if (err) {
      console.error('Error executing command 1:', err);
    } else {
      console.log('Command 1 executed successfully.');
    }
  });

  myRepl.eval('console.log("Executing command 2")', myRepl.context, 'history_callback', (err, result) => {
    if (err) {
      console.error('Error executing command 2:', err);
    } else {
      console.log('Command 2 executed successfully.');
    }
  });

  // Close the REPL after executing commands
  setTimeout(() => {
    console.log('Closing the REPL...');
    myRepl.close();
  }, 2000); // Close the REPL after 2 seconds
});

// Event handler for when REPL is closed
myRepl.on('close', () => {
  console.log('REPL closed.');
});

As the REPL API manuals does not give such a clear sample to demostrate how to close the REPL gracefully. I think complementing the document could be a quick solution. What's your advice here?

[LiST-GIT]

I think you're right, the programmer should determine the order of setupHistory and close themselves.

[lucshi]

I think I can submit a PR to resolve this issue even if the close is done ahead of setupHistory.
Feel free to reopen this issue @LiST-GIT