From: J-Van <joevandyk@...>
Date: 2006-11-11T09:29:10+09:00
Subject: Re: win32/process question

On 11/10/06, Park Heesob <phasis68@hotmail.com> wrote:
>
> Hi,
>
> >From: J-Van <joevandyk@gmail.com>
> >Reply-To: ruby-talk@ruby-lang.org
> >To: ruby-talk@ruby-lang.org (ruby-talk ML)
> >Subject: Re: win32/process question
> >Date: Sat, 11 Nov 2006 03:24:34 +0900
> >
> >On 11/10/06, Park Heesob <phasis68@hotmail.com> wrote:
> >>
> >>Hi,
> >>
> ....
> >> >
> >>Refer to http://msdn2.microsoft.com/fr-fr/library/ms686722.aspx,
> >>"While open handles to kernel objets are closed automatically when a
> >>process
> >>terminates, the objects themselves exist until all open handles to them
> >>are
> >>closed. Therefore, an object will remain valid after a process that is
> >>using
> >>it terminates if another process has an open handle to it."
> >>
> >>Here is the working code.
> >>
> >>irb(main):001:0> require 'win32/process'
> >>=> true
> >>irb(main):002:0> include Windows::Handle
> >>=> Object
> >>irb(main):003:0> info = Process.create :app_name=>'notepad'
> >>=> #<struct Struct::ProcessInfo process_handle=1916, thread_handle=1912,
> >>process
> >>_id=1748, thread_id=1108>
> >>irb(main):004:0> Process.kill 0,info.process_id
> >>=> [1748]
> >>irb(main):005:0> Process.kill 9,info.process_id
> >>=> [1748]
> >>irb(main):006:0> CloseHandle(info.process_handle)
> >>=> true
> >>irb(main):007:0> CloseHandle(info.thread_handle)
> >>=> true
> >>irb(main):008:0> Process.kill 0,info.process_id
> >>ProcessError: The parameter is incorrect.
> >>         from
> >>c:/ruby/lib/ruby/gems/1.8/gems/win32-process-0.5.1/lib/win32/proces
> >>s.rb:156:in `kill'
> >>         from
> >>c:/ruby/lib/ruby/gems/1.8/gems/win32-process-0.5.1/lib/win32/proces
> >>s.rb:132:in `each'
> >>         from
> >>c:/ruby/lib/ruby/gems/1.8/gems/win32-process-0.5.1/lib/win32/proces
> >>s.rb:132:in `kill'
> >>         from (irb):8
> >
> >So, if I use Process.create to create a new process, and I want to
> >know when a user closed the program, I should close the handle to the
> >process immediately after starting it?  And then Process.kill(0,
> ><pid>) would return an exception once the user closed the program?
> >
> >Joe
> >
> You cannot close the hanle if the process is still alive. You can use
> WaitForSingleObject or Process.waitpid to wait until child process exits
> like this:
>
> require 'win32/process'
> include Windows::Handle
> info = Process.create :app_name=>'notepad'
> Process.waitpid(info.process_id)
> CloseHandle(info.process_handle)
> CloseHandle(info.thread_handle)


If I use Process.waitpid in a thread, all the other threads seem to
block until the process that I'm waiting for stops.

I'm writing a program that runs on a windows machine that listens for
requests to start and kill programs.  It needs to be able to run and
kill multiple programs and needs to be able to monitor the programs
that it has started to make sure that they are still running.  If
Process.waitpid makes the whole Ruby process hang, that's no good.

Joe