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Author Topic: Tracking down a .net vs server memory issue  (Read 2413 times)
simmo
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« on: January 14, 2009, 06:17:04 pm »

Basically users are using .net pages to pull tons of data from a sql server. I can watch the available memory in iis drop and drop till the current user gets an error and any future attempts to pull up any .net page results in an 'out of memory' error until I /iisreset the server...

I've got 4gb of ram in the server, where should I start looking to get this fixed? I'm thinking its a 'garbage collection' error but I don't know if I need to change something in iis or blame the developer.
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wrack
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« Reply #1 on: January 15, 2009, 04:46:43 am »

Simmo,

Basically you should never get the 'out of memory' error in a web page. First thing I would do is check out the code and make sure there are no memory leaks. Next checkout and see how much memory is SQL Server is set to use. I normally keep 2GB for the OS and IIS to handle things and force SQL to use the rest.

If you are sure about the code that there are no memory leaks then it looks like your IIS is being hit really hard for requests and SQL Server is doing a lot of work to get the data out too so the first thing you need to do is setup some traces to do SQL Server performance tuning. I had a great article printed to PDF which showed which traces to set and how to come to a conclusion based on the result of each trace.

Unfortunately I am in India at the moment and won't be back to Aussie land till 8 more days so I can't post the file here.

Search for "SQL Server Performance Tuning" and you should find many things. Most probably the results would ask you to get more RAM and faster HDDs, keep LOG files on a different physical disk and stuff like that.

Hope this helps.
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simmo
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« Reply #2 on: January 15, 2009, 03:03:59 pm »

I'm pretty sure I have a copy of the pdf from when we were over taxing a sql server (its prolly attached to a thread on this forum) but I think we can rule out sql being the culprit as it is on another server, the web server is its own box.

I'm not real familiar with .net and didn't write the code so I personally can't check for leaks, but I trust that when I asked the developer to double check that everything was good, he did. His code is usually pretty clean and has the user in mind.

If I open the task manager on the server I can watch the w3wp.exe process just get fatter and fatter but never go down until I /iisreset (it might if i wait long enough, but usually the users wont let me Another Tounge)
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Jason Reed
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« Reply #3 on: January 15, 2009, 03:21:14 pm »

Do you know exactly which pages are maxing it out?
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simmo
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« Reply #4 on: January 15, 2009, 05:08:43 pm »

The developer does, we were all on the line when it was happening but I didn't make note of what page it was.
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