We believe we have a memory congestion problem. Not ground-breaking on itself, but what surprises me is that if the number of sessions on our ASP.NET site rises above a certain threshold (about 600 concurrently logged in users, around 40 requests / sec), the GC starts to choke.
We know that our application has some smaller memory leaks. But the ASP.NET application has 3.2GB space, the machine has 3.7GB. Even if the /3GB switch is not honored, this should give at least 2GB of available memory.
Running ASP.NET 3.5 on IIS6, Windows 2003, 32 bit. Once the total heap size of the ASP.NET application reaches about 1GB, the GC starts to take 80% on average, slowing down the whole site. [EDIT] At the same time, the heap memory is not a sawtooth anymore, but a flatline and the Gen-1 collections rises steeply. As far as I know, 1GB is not a limit for ASP.NET or IIS6, is it?
While we're in the process of tackling the problem at its source, is there something that you can think of that explains this behavior?
PS: during all this, the "available memory" counter in perfmon shows about 2500MB free.