Question

I have been developing a quite large application, and I uploaded it to my server some days ago. Now I have found out it has several memory leaks – Uh oh.
My server is running Windows Server 2008 on 1GB ram. When I have 0 people online, only 550-600mb is used. When one people comes online the memory starts skyrocketing, and if 3-4 people are online all 1GB ram is used.

The application is made in ASP.NET with AJAX. It has many updatepanels which runs every second and quite a lot of javascript. It uses 5-7 sessions at all times. I use LINQ to SQL as database communication.

I tried perfmon.exe on my server, and I found:

• Gen 0 collections goes from 0% to
  100% within minutes
• Gen 1 collections
  goes from 0% to 50% within 5 minutes
• Gen 2 is very close to 0% at all
  times
• Total heap bytes goes up to
  100% very fast

I also ran an analysis of my program with Visual Studio. 8% Of my total runtime is done in .ToList() methods, which properly is caused by LINQ to SQL.

My theories….

(1) Linq to SQL dataContext

This might be a crazy thing to do, but: In my data access layer I have a load of methods:

• AddSomethingToDatabase();
• AddSomethingElseToDatabase();
• DeleteSomethingFromDatabase();

Each of these has the following initialization:

GameDataContext db = new GameDataContext();

Which means the above statement runes nearly every second or more.

(2) No objects implement IDisposable

I have to be honest: I have never worked with IDisposable. As far as I have read, this might be a problem.

Also, if this is the leak, which classes should implement it? I do not have any I/O work or others, only the DataContext.

(3) Loads of UpdatePanels and jQuery

I have some fear loads of updatepanels can give problems with performance, but I do not know how to check it.

---

So my question is: Any ideas on what the memory leak could be? Any ideas on how to find the memory leak? And any ideas on how to solve it?

I would love to hear from someone who has experience with the situation above!

Thanks,
Lars

Answer 1

You absolutely must ensure that IDisposable objects get Dispose called when you are done with them. The simplest way to do this is to use using:

using (GameDataContext db = new GameDataContext())
{
    // code that uses 'db' goes in here
}

// Dispose called when 'using' scope ends

If you still have problems after doing this throughout, then profiling is needed, but fix this first since it’s a no-brainer.

Your own objects usually only need to implement IDisposable if they encapsulate unmanaged resources for which you wish to guarantee deterministic release back to the OS, so that those resources – file handles, sockets, and so on – are not sitting around waiting for GC for an interval of time you cannot rely on.

I don’t have an answer for your question 3), sorry.