How to retrieve performance counter for current asp.net application

Question

I want to retrieve some performance counters for the 'ASP.NET Applications' category from within my ASP.NET application.

My problem is, that I don't know how to determine the correct instance name for my current running ASP.NET application.

I currently use this code:

string instanceName = GetCurrentProcessInstanceName();

_perfCounters.Add(new PerformanceCounter("ASP.NET", "Application Restarts"));
_perfCounters.Add(new PerformanceCounter("ASP.NET Applications", "Pipeline Instance Count", instanceName));
_perfCounters.Add(new PerformanceCounter("ASP.NET Applications", "Requests Executing", instanceName));
_perfCounters.Add(new PerformanceCounter("ASP.NET Applications", "Requests/Sec", instanceName));
_perfCounters.Add(new PerformanceCounter("ASP.NET Applications", "Requests Failed", instanceName));

For GetCurrentProcessInstanceName I defined those helper methods from information and code snippets I found on the intertubes:

    private static string GetCurrentProcessInstanceName()
    {
        return GetProcessInstanceName(GetCurrentProcessId());
    }

    private static int GetCurrentProcessId()
    {
        return Process.GetCurrentProcess().Id;
    }

    private static string GetProcessInstanceName(int pid)
    {
        PerformanceCounterCategory cat = new PerformanceCounterCategory("Process");

        string[] instances = cat.GetInstanceNames();
        foreach (string instance in instances)
        {

            using (PerformanceCounter cnt = new PerformanceCounter("Process", "ID Process", instance, true))
            {
                int val = (int) cnt.RawValue;
                if (val == pid)
                {
                    return instance;
                }
            }
        }

        return null;
    }

Now the problem is, that I get the following error: Instance 'w3wp' does not exist in the specified Category.

So obviously, the code snippets don't return the correct instance ID for the current application.

My question is: How can I determine (reliable) the correct value?

Additional information: Since I learned that one should initially create a performance counter object and re-use this instance (vs. creating this object on every occasion you need this) I fire up a singleton when the application starts up. Out of this reason, I don't have access to a current HttpRequest, since this happens before a request hits the application.

Answer 1

I found the solution, and it's quite simpel:

string curentWebApplicationInstanceName = System.Web.Hosting.HostingEnvironment.ApplicationID.Replace('/', '_');