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Re: spawn [message #18945 is a reply to message #8682]

Wed, 16 February 2000 00:00

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

marc <m_schellens@hotmail.com> writes:

> I want to spawn under UNIX one program many times (multiprocessor
> machine). So I could sent it into the background using the UNIT keyword,
> but how can I determine when the program finishes?
> I run some basic tests and it seems that IDL leaves the unit open.
> Is there a way or have I (ab)use the filesystem for this (via
> lockfiles)?

A clarification is in order. SPAWN with the UNIT keyword does *not*
run the process in the background. The unit stays open because IDL
attaches the output of the process to the unit, and IDL is waiting for
you to read the output.

You can run the process in the background by adding '&' like you
normally would. Then be sure that you redirect the output and CLOSE
the unit.

To find out whether a background process is finished is difficult.
Usually it's just easiest to write a flag to a temporary file when the
job is done, and have IDL periodically monitor that file for changes.
One can probably do it with the unix system call waitpid(), but you
that would require compiling a DLM, not for the faint of heart.

Good luck,
Craig

--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		SPAWN By: Nobuyuki Tasaka on Tue, 08 April 1997 00:00
		Re: SPAWN By: alpha on Wed, 16 April 1997 00:00
		Re: SPAWN By: davidf on Fri, 11 April 1997 00:00
		Re: spawn By: marc schellens[1] on Thu, 17 February 2000 00:00
		Re: spawn By: marc schellens[1] on Thu, 17 February 2000 00:00
		Re: spawn By: Craig Markwardt on Wed, 16 February 2000 00:00
		Re: spawn By: Benno Puetz on Mon, 06 March 2000 00:00
		Re: Spawn By: Michael Galloy on Thu, 31 July 2008 10:21
		Re: Spawn By: mankoff on Thu, 31 July 2008 05:38
		Re: Spawn By: Joost Aan de Brugh on Thu, 31 July 2008 05:37
		Re: Spawn By: Bob[3] on Thu, 31 July 2008 05:33
		Re: Spawn By: Allan Whiteford on Thu, 31 July 2008 04:56

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