Hi,

I have a server which keeps on adding virtual shared memory segments (SHMADD).
Want to check if there is any culprit process contributing to this addition or I really need to increase SHMVIRTSIZE.

Possible causes I know might be:
1. Increase in number of connections.
2. Dynamically allocated locks.
3. Backup.

What else can I check to see if there is any Application process which can be tuned ?
What are the contributors for virtual shared memory segment addition ?

Thanks for the help !!


------------------------------
Rajat Agrawal
------------------------------

#Informix

Hi Rajat,

In rare cases, a memory leak may occur because the statement does not close in the application code.
There may be sessions that increase memory usage with poorly written code that way.
You may also want to monitor high session memory usage with the onstat -g ses command or sysmaster information.

------------------------------
SangGyu Jeong
Software Engineer
Infrasoft
Seoul Korea, Republic of
------------------------------

Thanks SangGyu !

------------------------------
Rajat Agrawal
------------------------------

Original Message:
Sent: Mon February 24, 2020 10:42 AM
From: SangGyu Jeong
Subject: Virtual Shared memory segment

Hi Rajat,

In rare cases, a memory leak may occur because the statement does not close in the application code.
There may be sessions that increase memory usage with poorly written code that way.
You may also want to monitor high session memory usage with the onstat -g ses command or sysmaster information.

------------------------------
SangGyu Jeong
Software Engineer
Infrasoft
Seoul Korea, Republic of
------------------------------

------Original Message------

Hi,

I have a server which keeps on adding virtual shared memory segments (SHMADD).
Want to check if there is any culprit process contributing to this addition or I really need to increase SHMVIRTSIZE.

Possible causes I know might be:
1. Increase in number of connections.
2. Dynamically allocated locks.
3. Backup.

What else can I check to see if there is any Application process which can be tuned ?
What are the contributors for virtual shared memory segment addition ?

Thanks for the help !!


------------------------------
Rajat Agrawal
------------------------------

#Informix

------Original Message------

Hi,

I have a server which keeps on adding virtual shared memory segments (SHMADD).
Want to check if there is any culprit process contributing to this addition or I really need to increase SHMVIRTSIZE.

Possible causes I know might be:
1. Increase in number of connections.
2. Dynamically allocated locks.
3. Backup.

What else can I check to see if there is any Application process which can be tuned ?
What are the contributors for virtual shared memory segment addition ?

Thanks for the help !!


------------------------------
Rajat Agrawal
------------------------------

#Informix

Have a look at the output of "onstat -g mem". The largest pools can be viewed with:

onstat -g mem | sort -k4 -nr | head -20

That might give some clues. You are only interested in those with class V (virtual) as others are fixed.

If this is a gradual long-term problem, you have a very large number of pools named RA_req_*, and Automated Update Statistics is enabled in the Task Scheduler, you may have encountered a bug we worked through with IBM who reported this:

"The defect APAR IT31418 will be fixed in the next maintenance release of IDS 12.10 and 14.10:

idsdb00104976 -> IDS 12.10.xC14 --> planning to be released around 12 March
idsdb00105034 -> IDS 14.10.xC4 --> planning to be released around 11 June
 
This defect has been caused by a memory leak that seems to happen with RA_REQ_PAGELIST request only."

------------------------------
Doug Lawry
------------------------------

Hi Doug,

Thank you for sharing information about the defects and release date of the next fix pack!

------------------------------
SangGyu Jeong
Software Engineer
Infrasoft
Seoul Korea, Republic of
------------------------------

Original Message:
Sent: Tue February 25, 2020 05:16 AM
From: Doug Lawry
Subject: Virtual Shared memory segment

Have a look at the output of "onstat -g mem". The largest pools can be viewed with:

onstat -g mem | sort -k4 -nr | head -20

That might give some clues. You are only interested in those with class V (virtual) as others are fixed.

If this is a gradual long-term problem, you have a very large number of pools named RA_req_*, and Automated Update Statistics is enabled in the Task Scheduler, you may have encountered a bug we worked through with IBM who reported this:

"The defect APAR IT31418 will be fixed in the next maintenance release of IDS 12.10 and 14.10:

idsdb00104976 -> IDS 12.10.xC14 --> planning to be released around 12 March
idsdb00105034 -> IDS 14.10.xC4 --> planning to be released around 11 June
 
This defect has been caused by a memory leak that seems to happen with RA_REQ_PAGELIST request only."

------------------------------
Doug Lawry
------------------------------