topic Re: Any clues on what would do this to a process? in Operating System - HP-UX

Any clues on what would do this to a process?

JJ_4 — Wed, 20 May 2009 13:47:22 GMT

So, on an HP Itanium machine, a process is running, and then just "disappears".

Review of the syslog shows :

vmunix: Pid 6251 was killed due to failure in writing the User register stack- possible stack overflow.

What signal would the O/S (if it was the O/S) send the process?

Re: Any clues on what would do this to a process?

Fabian Briseño — Wed, 20 May 2009 14:15:42 GMT

Hello JJ.
What OS version ?

What process is causing this, DB, application ?

Since when is thi happening ?

Re: Any clues on what would do this to a process?

TTr — Wed, 20 May 2009 14:22:20 GMT

> possible stack overflow

Check the stack size in the kernel. If you have not changed it from the default size, consider increasing it if you think or you know that this process requires a large stack size. Otherwise the process has a bug or it was not meant to run on itanium based HP-UX.

Re: Any clues on what would do this to a process?

Fabian Briseño — Wed, 20 May 2009 14:24:03 GMT

Hello JJ.
Maybe the following thread will help.

http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1242832524002+28353475&threadId=861749

Re: Any clues on what would do this to a process?

JJ_4 — Wed, 20 May 2009 14:33:27 GMT

HP-UX Itanium 11.23

This is a set of processes which make up a Database Environment (generally two or more processes will be killed as above).

ulimit shows stacksize as a huge 128Mb ... so doubt it is actual "stack" overflow.

Machine had been up for 100 days and "no changes".

Increase the kernel stack size?? What parameter is that?

Re: Any clues on what would do this to a process?

TTr — Wed, 20 May 2009 14:39:10 GMT

It's maxssiz and maxssiz_64bit. Whatever you database is, check if there are other kernel parameter settings that are recommended for this particular database.

Re: Any clues on what would do this to a process?

Fabian Briseño — Wed, 20 May 2009 14:47:08 GMT

Hello JJ.
More threads to check.

http://docs.hp.com/en/TKP-90202/TKP-90202.pdf

Re: Any clues on what would do this to a process?

Steven E. Protter — Wed, 20 May 2009 15:03:52 GMT

Shalom,

ulimit is not the only possible cause.

maxdsiz
maxssiz

and their 64 bit mates can all be part of this issue.

It is likely you will need to reboot your system to make all the required kernel changes.

SEP

Re: Any clues on what would do this to a process?

Don Morris_1 — Wed, 20 May 2009 15:35:41 GMT

No, you should check maxrsessiz / maxrsessiz_64bit -- note that you had a failure writing the *register stack*. In particular, you should get this message when the RSE stack write fails while trying to process a signal for a process in the kernel (and the kernel sends the kill signal to the process after the message).

Re: Any clues on what would do this to a process?

Dennis Handly — Thu, 21 May 2009 06:02:04 GMT

> ulimit shows stacksize as a huge 128Mb ... so doubt it is actual "stack" overflow.

Perhaps you have infinite recursion so no matter how big you make it, you will always die. Make this smaller so you will die here first vs the RSE stack below.
It would be good to look at a stack trace from a core file.

Also, if you are on a thread stack, changing maxssiz or maxrsessiz won't help.

>Don: you should check maxrsessiz / maxrsessiz_64bit

I've only had to increase this to 16 Mb for one heavily recursive application.
Unfortunately you'll have to reboot to change this.

Re: Any clues on what would do this to a process?

JJ_4 — Wed, 27 May 2009 13:33:19 GMT

Many thanks for the answer.

It was basically an unintended recursion :-/ (signal handling whilst signal handling whilst signal handling etc.)

So, it blowing the register stack was sort of expected.

Re: Any clues on what would do this to a process?

JJ_4 — Wed, 27 May 2009 14:02:23 GMT

:-/ Oh web forms

Re: Any clues on what would do this to a process?

Dennis Handly — Wed, 27 May 2009 20:28:20 GMT

If you are happy with the answers you have gotten, please read the following on how to reopen threads and to assign points:
http://forums.itrc.hp.com/service/forums/helptips.do?#41
http://forums.itrc.hp.com/service/forums/helptips.do?#33