topic Re: CPU busy for a detached process in Operating System - OpenVMS

CPU busy for a detached process

Sk Noorul Hassan — Wed, 14 Sep 2005 06:03:03 GMT

Hi,
When running a dcl script as detached procees, it is taking almost 90% of CPU time. The script monitors the system error messages continuously and notifies the operator if it receives any potential error string on message. So, is there any idea how to reduce the CPU usage or this script can be submitted in other way which will have less impact on the system. Pls suggest..

Re: CPU busy for a detached process

Bojan Nemec — Wed, 14 Sep 2005 06:08:59 GMT

Hassan,

You can put a reasonable wait in the script loop. The other posibility is to reduce the process priority to minimum but in this case the process will also take all the idle CPU time.

Bojan

Re: CPU busy for a detached process

Ian Miller. — Wed, 14 Sep 2005 06:09:20 GMT

How does the DCL procedure monitor the system error messages?

Re: CPU busy for a detached process

Hein van den Heuvel — Wed, 14 Sep 2005 06:49:03 GMT

May we assume that you tested the script interactively and it presented a reasonable load, but when putting in production, detached, it became unreasonable?

What timeout / poll mechanisme do you use?

Is is something like a basic SLEEP where it either waits on a time to elaps, or for terminal action? Running detached there will be no terminal to wait on, and a timeout based on that could well fail.

Hein.

Re: CPU busy for a detached process

Antoniov. — Thu, 15 Sep 2005 01:42:15 GMT

It sounds like detached process run differently from intereactive one.
May be your dcl procedure asks for interactive terminal and when detached goes into error section and loops infinitely.
Have you some log?

Antonio Vigliotti

Re: CPU busy for a detached process

Sk Noorul Hassan — Thu, 15 Sep 2005 06:57:38 GMT

The DCL script uses the f$search to locate for the latest error which is generated as part of application errors in the system.We keep a log of 500 such errors. So, whenever any new warning message generates, the dcl script takes this to a file and in a perticular line it searches for a string, If it gets that string it will notify otherwise it will again go to loop for searching the latest warning message.when I am giving some time wait, the CPU usage gets reduced to almost negligible. But buffered I/O usage looks 10 to 20 in MON SYSTEM command. So, will it be ok to go ahead with a time wait in the loop, as I do not want to miss the error messages.

I am submitting this DCL script using run loginout.exe/input=dcl script/output=nl:/detached

Re: CPU busy for a detached process

Antoniov. — Thu, 15 Sep 2005 07:03:55 GMT

Did you execute that dcl procdure interactively?
Also try adding /prio=1

Antonio Vigliotti

Re: CPU busy for a detached process

Robert_Boyd — Thu, 15 Sep 2005 08:08:28 GMT

You might try varying the wait time in the loop. The amount of CPU used will depend entirely on how long you make the wait time.

I like to use a symbol to set the wait time as a parameter in the beginning of any DCL script. Then in the wait loop I refer to the symbol:

$ delta_wait = "0:0:10.0"
$ ...

$LOOP:
$ < do some things>
$ wait 'delta_wait'
$ goto LOOP

Have you thought about setting up another mechanism to receive the messages? It would be more efficient if you could read the messages continuously with normall queued IO either from a mailbox or shared read access to the file. Have you considered these and other possibilities?

Robert

Re: CPU busy for a detached process

Sk Noorul Hassan — Thu, 15 Sep 2005 11:10:35 GMT

Roberts, Thanks for the suggestions. Can you please guide me for the queued IO read mechanism ?

Re: CPU busy for a detached process

Thomas Ritter — Thu, 15 Sep 2005 23:35:05 GMT

May we examine the script for constructive comment ?

Re: CPU busy for a detached process

Ian Miller. — Fri, 16 Sep 2005 04:00:24 GMT

The programming concepts manual is always a good place to start when looking for other ways to do something.
http://h71000.www7.hp.com/doc/82FINAL/5841/5841PRO.HTML