childprocess kills detached windows process on exit about childprocess HOT 4 CLOSED

Thanks for opening an issue @soapy1!

Digging into this a little further, what I can see is that we set the DETACHED_PROCESS flag passed to the CreateWindowsW function call.

The Win32 API documentation for the DETACHED_PROCESS flag suggests we are using it incorrectly. "Detach" in this context simply means the process isn't attached to the same console/terminal as the parent, whereas "detach" in the way ChildProcess uses it is more referring to the Process::detach helper.

I unfortunately do not have easy access to a Windows machine at this time, but I wonder if simply calling Process::detach in ChildProcess::Windows::ProcessBuilder.start would do the trick. Since you are running this on Windows, would you be able to apply the following diff and running locally to see if it fixes your issue? It may not, as Process::detach may be specific to Unix systems. Would happily accept a pull request if it works, however!

See lib/childprocess/windows/process_builder.rb

        def start
          create_command_pointer
          create_environment_pointer
          create_cwd_pointer

          setup_flags
          setup_io

          pid = create_process
+         Process.detach(pid) if @detach
          close_handles

          pid
        end

Appreciate your help!

from childprocess.

Thanks for digging into this!
I applied the patch and it looks like it returns an error.

C:\Users\vagrant\Desktop\test>ruby bug.rb
Parent process started
Traceback (most recent call last):
        5: from bug.rb:4:in `<main>'
        4: from bug.rb:20:in `<class:ProcessTest>'
        3: from bug.rb:14:in `start'
        2: from C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/childprocess-3.0.0/lib/childprocess/abstract_process.rb:81:in `start'
        1: from C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/childprocess-3.0.0/lib/childprocess/windows/process.rb:70:in `launch_process'
C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/childprocess-3.0.0/lib/childprocess/windows/process_builder.rb:35:in `start': undefined method `detach' for ChildProcess::Windows::Process:Class (NoMethodError)

I made a slight modification to ::Process.detach(pid) if @detach. This doesn't produce an error, however the problem persists.

from childprocess.

I dug into this a little more and I found that JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE is getting set. From the windows docs on managing jobs it looks like setting this flag will kill a child process when the parent terminates as part. Here is a little PR for not setting that flag if running in detached mode #167

from childprocess.

Thank you for digging into this and submitting a PR in #167. Closing as while we don't have any tests, I am assuming this solved the issue for you locally. Thanks again!

from childprocess.