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Console process order changed in 15063's v2 console making npm harder to close #126

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opened 2026-01-30 21:43:09 +00:00 by claunia · 0 comments
claunia commented 2026-01-30 21:43:09 +00:00
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Originally created by @bitcrazed on GitHub (Feb 16, 2018).

Originally assigned to: @miniksa on GitHub.

From @rprichard on May 29, 2017 4:40

In 15063's v1 console, and any console in Windows 10.0.14393 and older, Windows seems to order the processes from newest-to-oldest for GetConsoleProcessList (probably the opposite of the attachment order). When a console is closed, Windows considers each process, in order, and delivers it a CTRL_CLOSE_EVENT event. Windows gives the process 5 seconds to exit, after which point it terminates the process.

In 15063's v2 console, the order of the process list has reversed and is now oldest-to-newest. Maybe the change was intentional? Regardless, it affects npm (the node package manager), as detailed here: https://github.com/Microsoft/vscode/issues/26807#issuecomment-304503591.

The test case given on https://github.com/Microsoft/vscode/issues/26807 was fairly easy for me to reproduce, and it doesn't require VSCode. Installing node.js adds node.bat and npm.cmd to the PATH. Run the commands in an ordinary console, and instead of "pressing the garbage bin button", try to close the console window. In my experience, the first click leaves the youngest node.exe process running, and the second click finishes the job. (VSCode's "garbage bin button" eventually turns into winpty posting a WM_CLOSE message, which kills winpty-agent.exe. The console window survives, but it's hidden, so the node.exe is leaked.)

Starting in Windows 8, when the console is delivering CTRL_CLOSE_EVENT events, it seems to abort the operation if a process exits on its own accord. Windows 7, on the other hand, skips over dead processes.

The combination of the 15063 v2 change and the Win8 change breaks npm, which has a process tree like so:

  • A: node.exe (npm run, owns Job1)
    • B: cmd.exe (assigned to Job1)
      • C: node.exe (tsc --watch)

Windows delivers CTRL_CLOSE_EVENT to A(node.exe). node.exe turns it into a libuv-emulated SIGHUP signal, which is sent to Node's main thread and ignored. After 5 seconds, Windows kills A(node.exe). Killing A(node.exe) destroys Job1, which destroys B(cmd.exe). Apparently the console then aborts the close operation because B(cmd.exe) is missing.

Previously, Windows signaled C(node.exe) first, and after C exited, the other two processes would definitely exit.

Also: There seems to be a race condition between process cleanup (in the kernel?) and the close event signaling (in conhost.exe?), and sometimes the console close operation is able to skip over already-dead processes.

I wrote a test program demonstrating things discussed in this report -- closetest.cc, https://gist.github.com/rprichard/7ec3fe1b199f513bee82fea196a82a79. It has notes at the top of the file and a --help option.

  • To see the change in signaling order (EXAMPLE 1 in closetest.cc), run Sysinternals dbgview.exe, then closetest.exe without arguments.

  • To create a console that's hard to close (EXAMPLE 2), run closetest.exe -d alternate --gap -n N. In Windows 8 and up, you'll have to close the console N + 1 times. In Vista or Windows 7, just once is enough.

  • To see the race condition (EXAMPLE 3), try:

    • closetest.exe -d [backward/forward] -m job -n 10 --alloc 1, or
    • closetest.exe -d [backward/forward] -m job -n 50

    On a v1 or <= 14393 console, use -d backward. On the v2 15063 console, use -d forward.

  • The closest analog to npm's issue is closetest.exe -d forward -m job -n 2 --alloc 100. With the 15063 v2 console, this command usually takes two Close clicks to destroy the console.

Windows build number: 10.0.15063.332

Copied from original issue: Microsoft/WSL#2170

Originally created by @bitcrazed on GitHub (Feb 16, 2018). Originally assigned to: @miniksa on GitHub. _From @rprichard on May 29, 2017 4:40_ In 15063's v1 console, and any console in Windows 10.0.14393 and older, Windows seems to order the processes from newest-to-oldest for `GetConsoleProcessList` (probably the opposite of the attachment order). When a console is closed, Windows considers each process, in order, and delivers it a `CTRL_CLOSE_EVENT` event. Windows gives the process 5 seconds to exit, after which point it terminates the process. In 15063's v2 console, the order of the process list has reversed and is now oldest-to-newest. Maybe the change was intentional? Regardless, it affects npm (the node package manager), as detailed here: https://github.com/Microsoft/vscode/issues/26807#issuecomment-304503591. The test case given on https://github.com/Microsoft/vscode/issues/26807 was fairly easy for me to reproduce, and it doesn't require VSCode. Installing node.js adds `node.bat` and `npm.cmd` to the PATH. Run the commands in an ordinary console, and instead of "pressing the garbage bin button", try to close the console window. In my experience, the first click leaves the youngest `node.exe` process running, and the second click finishes the job. (VSCode's "garbage bin button" eventually turns into winpty posting a `WM_CLOSE` message, which kills `winpty-agent.exe`. The console window survives, but it's hidden, so the `node.exe` is leaked.) Starting in Windows 8, when the console is delivering `CTRL_CLOSE_EVENT` events, it seems to abort the operation if a process exits on its own accord. Windows 7, on the other hand, skips over dead processes. The combination of the 15063 v2 change and the Win8 change breaks npm, which has a process tree like so: * A: node.exe (npm run, owns Job1) * B: cmd.exe (assigned to Job1) * C: node.exe (tsc --watch) Windows delivers `CTRL_CLOSE_EVENT` to A(node.exe). node.exe turns it into a libuv-emulated SIGHUP signal, which is sent to Node's main thread and ignored. After 5 seconds, Windows kills A(node.exe). Killing A(node.exe) destroys Job1, which destroys B(cmd.exe). Apparently the console then aborts the close operation because B(cmd.exe) is missing. Previously, Windows signaled C(node.exe) first, and after C exited, the other two processes would definitely exit. Also: There seems to be a race condition between process cleanup (in the kernel?) and the close event signaling (in `conhost.exe`?), and sometimes the console close operation is able to skip over already-dead processes. I wrote a test program demonstrating things discussed in this report -- `closetest.cc`, https://gist.github.com/rprichard/7ec3fe1b199f513bee82fea196a82a79. It has notes at the top of the file and a `--help` option. * To see the change in signaling order (EXAMPLE 1 in `closetest.cc`), run Sysinternals `dbgview.exe`, then `closetest.exe` without arguments. * To create a console that's hard to close (EXAMPLE 2), run `closetest.exe -d alternate --gap -n N`. In Windows 8 and up, you'll have to close the console N + 1 times. In Vista or Windows 7, just once is enough. * To see the race condition (EXAMPLE 3), try: * `closetest.exe -d [backward/forward] -m job -n 10 --alloc 1`, or * `closetest.exe -d [backward/forward] -m job -n 50` On a v1 or <= 14393 console, use `-d backward`. On the v2 15063 console, use `-d forward`. * The closest analog to npm's issue is `closetest.exe -d forward -m job -n 2 --alloc 100`. With the 15063 v2 console, this command usually takes two Close clicks to destroy the console. Windows build number: 10.0.15063.332 _Copied from original issue: Microsoft/WSL#2170_
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