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max_tread_proc exceeded

 
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Dave Polshaw
Frequent Advisor

max_tread_proc exceeded

We recently observed that the vxfsd process was using 541 threads against to the max_thread_proc value of 512.

kmtune confirms that max_thread_proc is indeed 512 and the number of threads (541) was observed from glance.

An extract from the glance screen follows -
(Sorry - I cannot format the screen but the 541 figure was under the 'Thrd Count' header -

vxfsd 41 root 0.8 541 44.8

How can a process exceed the maxinum number of threads and how come vxfsd is using so many anyway?

Thanks in anticipation.

Dave

Cheers

Dave
Knowledge speaks. Wisdom listens...
14 REPLIES 14
Kapil Jha
Honored Contributor

Re: max_tread_proc exceeded

Are you sure u looking at the right thing?
How do u loooking this in glance.

BR,
Kapil+
I am in this small bowl, I wane see the real world......
Dave Polshaw
Frequent Advisor

Re: max_tread_proc exceeded

On the main glance screen the 5th column along is the thread count. So I am led to believe!
Knowledge speaks. Wisdom listens...
Dennis Handly
Acclaimed Contributor

Re: max_tread_proc exceeded

>the 541 figure was under the 'Thrd Count'

That seems obvious enough.
Perhaps system demons aren't like you and me and can bypass these limits?

> On the main glance screen the 5th column along is the thread count.

In gpm, mine just happens to be column 8.
And my vxfsd now has 34 threads.
Dennis Handly
Acclaimed Contributor
Solution

Re: max_tread_proc exceeded

You can also use my example program that uses pstat_getlwp(2) to count the number of threads for that PID:
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1296647
Kapil Jha
Honored Contributor

Re: max_tread_proc exceeded

I am not sure Denice if it can increase on its own, I have never seen this kindda behaviour.

http://docs.hp.com/en/B3921-90010/max_thread_proc.5.html

this says threads can not exceed this limit
:(

BR,
Kapil+
I am in this small bowl, I wane see the real world......
Dennis Handly
Acclaimed Contributor

Re: max_tread_proc exceeded

>I have never seen this kindda behaviour.

Right, that's why double checking the number of threads would be helpful. I hope max_thread_proc wasn't decreased recently. That would leave the thread pigs orphaned.
Dave Polshaw
Frequent Advisor

Re: max_tread_proc exceeded

Hi. Thanks all for your input. Points on the way. We cannot, unfortunately, install or run any unsupported routines on these machines due to political circumstances but I have pointed out that there are routines which will, hopefully, be more accurate than the glance stats. The max_thread_proc has not been increased or decreased recently so I do not believe that is an issue. I think the nearest we can get to it is that the number of threads was high for the 5 second glance refresh window. I am not sure how glance calculates it stats but if, for instance, it was dropping old threads and starting new ones at the rate of 20 per second I could understand how the 5 second counter would show more than the maximum number for a short period of time. Does that make sense to anyone or can anyone provide any information to back up or refute the theory?

Thanks again

Dave
Knowledge speaks. Wisdom listens...
Dennis Handly
Acclaimed Contributor

Re: max_tread_proc exceeded

>Does that make sense to anyone?

I would think glance would call pstat_getlwp(2) once during the 5 seconds and shouldn't get too many threads.

I'm not sure if anyone asked but why do you care how many threads are used by vxfsd, do you have a real problem?
Dave Polshaw
Frequent Advisor

Re: max_tread_proc exceeded

Hi Dennis. You are right of course and, as long as it is working, it does not really matter but it was a question by a user who has access to glance. You know what they say about a little knowledge being dangerous! It is academic but I must say it intrigued me as to why the absolute limit has been exceeded, hence the question. Thanks for your time anyway.
Knowledge speaks. Wisdom listens...