End of output occasionally missing with "closeOnExit": "never"

[ltrzesniewski]

Windows Terminal version

1.23.10353.0

Windows build number

10.0.22631.0

Other Software

Build one of those (as is more convenient):

using System;

public static class Program
{
    public static void Main()
    {
        for (var i = 0; i <= 20_000; ++i)
            Console.WriteLine($"LINE: {i}");
    }
}

#include <iostream>

int main(int argc, char* argv[])
{
    for (int i = 0; i <= 20000; ++i)
        std::cout << "LINE: " << i << std::endl;

    return 0;
}

fn main() {
    for i in 0..=20_000 {
        println!("LINE: {i}");
    }
}

Steps to reproduce

• In your default profile settings, set Advanced -> Profile termination behavior to "Never close automatically"
  JSON equivalent:

  "profiles": {
    "defaults": {
      "closeOnExit": "never"

• Build one of the source codes provided above

• Double-click on the compiled exe file (do not run it from a shell)

Expected Behavior

The output should always end with the following lines:

LINE: 19995
LINE: 19996
LINE: 19997
LINE: 19998
LINE: 19999
LINE: 20000

[process exited with code 0 (0x00000000)]
You can now close this terminal with Ctrl+D, or press Enter to restart.

Restarting the process by pressing Enter any number of times should not change this outcome.

Actual Behavior

Most of the time, the behavior is as expected: the last line reads LINE: 20000.

However, after restarting the execution several times by pressing Enter, you can end up on an incomplete output, such as:

In the case of the C++ app, I even got the output cut in the middle of a line:

Getting this output may require 10 to 20 attempts, so please be patient. 😅

The problem is not reproducible when looping from a bat file:

@echo off
:loop
ConsoleApp.exe
pause
goto loop

However, a bat file which just runs the exe will reproduce the problem.

[carlos-zamora]

Thanks for filing! (Some psychic debugging from @lhecker) We might be missing a wait call in the VTIO class, which may not wait (on shutdown) to finish flushing to the output pipe. If that's the case, should be an easy fix 😊