Application Hanging - where to start?

[E3xtc]

Hi All,

**apologies if this is in the wrong section - however if this is please let me know which one is more appropriate - as I have already posted under Win2K3 forum**

We have an application which is hanging periodically - appears to be relativly random in time frame, however is generally always associated with a given application.

I have run perfmon logging the following:
Pages/Sec
% Committed Bytes in Use
Disk reads/sec
Avg Disk Queue Length
Interrupts/sec
% Processor
Total Sessions

When the application hangs it doesn't appear to be linked with any of the above items.

The application is a vb application, which runs off a SQL backend.
I have the same perfmon stats on the SQL server - however this also fails to show anything of interest.

Server is Win2K3 Term Serv, Dual Xeon 3ghz, 2gig ram, approx 15-20 users, 15krpm drives
SQL server is same spec except not a Term Serv.
Neither server is working hard at all.....

Is anyone able to give me any hints on things that I should be looking for which might give me an insight as to why it is hanging? (ie I could very well be missing an important item in perfmon)

I understand this is probably a "how long is a peice of string" question, however I just need some ideas on where I can go to hopefully get an answer.

Thanks in advance
Troy

 

[hmckillop]

I have seen applications "hang" when they effectively get in an infinite loop situation - Have you the capacity to debug the application ?
Alternatively you can try and see if the database communicating with the APP ok, but running SQLprofiler - ensuring you have both the RPC Starting and RPC Completing events switched on - this should show you the procs being called and if they complete - its handy if you know the time the app hangs at.
Have you checked the locks on the database to see if blocking is occuring at the time the application hangs - what are the timeouts set to for the app connections? (You can add perf mon stats for db lock timeouts)


Have you looked at the App logs, SQL logs - you could try changing your app to include verbose logging to capture the where in the code it falls over .

Just my 2 cents

"Own only what you can carry with you; know language, know countries, know people. Let your memory be your travel bag.

 

[E3xtc]

Thanks for the response!
The app is communicating fine with the database (or at least I think they are as 90% of the time the app runs fine)- Will have a play with profiler and see if I can see anything worth mentioning.

The deadlocks/blocking was one thing that I forgot to look for (THANKS!!!)

Will post back if I find anything useful - thanks again!