Troubleshoot Possible Memory/Slowdown Problems

[Tappy Tibbons]

We have rolled out an app, and are experiencing complete application and
system slowdown as users open and close windows forms in our app throughout
the day.

It usually happens about 50 or so form opening/closing cycles.

If the user notices the app is slowing down, and they exit the app then go
back in, it works fine for another 50 or so open/closes.

If they keep pushing it, and go another 20-30 times, it will eventually be
so slow the form takes 2-3 minutes to redraw, and will eventually lock their
PC, forcing a reboot.

The forms do have quite a few controls on them. They do talk to a database,
but not using bound forms, and the data access is pretty small.

We have tried setting all objects to nothing at the end of all procedures,
doing GC.Collect, other things, but can't quite nail it down...

The client machines are all WinXP SP1, P4 2.XGhz, 512MB RAM or better.
Version 1.0 of the framework, VS2002.

Any ideas on troubleshooting this? Is there a specific memory counter
somewhere I can monitor or display on the form, so I can see if it goes
down? The task manager memory for the app grows and grows, but I understand
that may not be a real accurate gauge of memory usage.

Thanks!

 

[Stuart Wells]

Sounds like you are bleeding memory - not necessarily of
your own making.

I use the following tool to detect this sort of behaviour:
http://www.scitech.se/memprofiler/Default.htm

In my experience I have found that any classes I have
written clean up perfectly (most of the time ;-) but some
standard components do not.

The most frequent offender is the menuitem component -
especially if you are using dynamic menuitem creation.

I believe there is a bug in the Framework which causes
duplicate (cloned) menuitems to be created but not
destroyed when menuitem merges take place (such as
MDIChild to parent menu merges). These I cannot cure
(unless someone knows how?).

Try extending the dispose method on the form to explicitly
unregister ALL the menuitem event handlers - I know this
seems a lot of work but it stopped exactly what you are
explaining in my application.

Stuart

 

[Tappy Tibbons]

Thanks for the tip, and the URL. I will try running it. I have never used
one of these. Is it pretty self explanatory, or am I looking at a lot of
work to get it installed, running, and learning it's operation?

We are not really doing any menuing at all in this app.

Any other ideas?

 

[Steve Austin]

Just a quick question - are you using standard controls, or custom ones?

 

[Tappy Tibbons]

Both... Also controls from 2 different 3rd parties. The form is the main
screen for some heavy duty power user CSR's.

That's what makes it so difficult to troubleshoot or to even try to pinpoint
where the problem could be....

 

[Joe White]

Are you using any UpDownControls? There's a known bug with those -- in
general, a form that contains an UpDownControl will never get
garbage-collected. I saw another thread in this NG within the past two
or three days that discussed this and mentioned a workaround.