topic Re: detach process in Operating System - OpenVMS

detach process

adarsh_4 — Thu, 05 Nov 2009 01:53:54 GMT

what could be some reasons why a detach process stops. How else can we see why the detach process stopped apart from the log file

thanks

Re: detach process

John Gillings — Thu, 05 Nov 2009 02:06:44 GMT

adarsh,

A detached process is like any other process. It stops because it was told to, it was deleted, it encountered a fatal error.

If you have accounting enabled, there should be an accounting record for the process termination that will have the termination status. That might give a clue.

In future, make sure you have an output file and error file defined for the process.

Re: detach process

labadie_1 — Thu, 05 Nov 2009 08:10:46 GMT

And when you start a detached process, you have the /output=file qualifier, that can help you understand what happens.

Better avoid the detached processes, and prefer the batch ones, you will avoid some problems and have the same functionalities.

Re: detach process

adarsh_4 — Thu, 05 Nov 2009 09:33:40 GMT

thanks, i was reading about /after qualifier in submit command. can u guys tell me where can i read some more about assigning time, so that the job gets resumbit after 2 seconds

Or can u guys tell me how to go about it

Re: detach process

labadie_1 — Thu, 05 Nov 2009 10:26:32 GMT

The cost of a process creation is huge on VMS compared to Unix.
So you should stay in the process, and loop with a
$ wait 00:00:02
instead of re-submitting.

What do you need to do every 2 seconds ?

Re: detach process

Hoff — Thu, 05 Nov 2009 12:26:49 GMT

Answering several different aspects of this thread...

Where can you get more information on SUBMIT and on time and time specification syntax? Start with the OpenVMS User's Guide and then (either or both, and depending on your goals) the OpenVMS System Manager's manuals and the OpenVMS Programming Concepts manual. The User's Guide will get you going, the System Manager's manual covers various tasks, and the Programming Concepts and other manuals cover details that will be of interest to programmers. Including time and timekeeping.

As for your literal question, there are specific details in the HELP library, too. The path to this help text has changed from time to time, which is why we generally ask that the OpenVMS version always be included when asking questions.

I just checked an OpenVMS Alpha V8.3 help library, and the HELP section here is HELP DATE_TIME.

Basic examples of SUBMIT /AFTER are available here:

http://labs.hoffmanlabs.com/node/97

This is off into job-scheduling, and the above article has links to cron and Kronos, and there are other open source and commercial schedulers around for OpenVMS.

The usual spot for debugging a detached process is in its own output log (see the sys$output when the process is created, depending on exactly how the detached process is created), or by bringing up the debugger if the application is running some sort of an executable image.

Here is an overview of detached processes and the OpenVMS debugger:

http://labs.hoffmanlabs.com/node/803

If you do not know how to use the OpenVMS debugger (and you're doing application debugging), stop what you're doing and go learn. Seriously. The payback from having even a passing knowledge of the debugger is massive.

Providing some more details on how the detached process is being launched (and around why you think SUBMIT /AFTER might help) could be useful in reaching an answer better tailored for your particular situation here.

And as has been discussed in this thread, starting or restarting a process every two seconds is usually not the most efficient solution.

Re: detach process

Steve Reece_3 — Fri, 06 Nov 2009 22:34:33 GMT

Normally, detached processes run programs and batch jobs run DCL. This is directly what the difference is in process setup, as well as that batch jobs also need to go through the job controller and the queue manager.
The trick with the detached process to get it to run DCL is to get the detached process to run LOGINOUT.EXE and use the Dcl as a /INPUT= on the RUN command:
e.g. RUN/INPUT=MYFILE.COM sys$system:loginout.exe

Re: detach process

adarsh_4 — Wed, 11 Nov 2009 23:08:56 GMT

thank you all, i have learnt a lot. thanks once again. you guys are really rocking.

Re: detach process

Art Wiens — Thu, 12 Nov 2009 03:33:07 GMT

... and rolling.

Sorry, someone had to say it.

Cheers,
Art