Get Performance Counter Instance Name (w3wp#XX) from ASP.NET worker process ID

Question

Hello,

I would like to display some memory statistics (working set, GCs etc.) on a web page using the .NET/Process performance counters. Unfortunately, if there are multiple application pools on that server, they are differentiated using an index (#1, #2 etc.) but I don't know how to match a process ID (which I have) to that #xx index. Is there a programmatic way (from an ASP.NET web page)?

Thank you very much.

Answer 1

The first hit on Google:

Multiple CLR performance counters appear that have names that resemble "W3wp#1"

When multiple ASP.NET worker processes are running, Common Language Runtime (CLR) performance counters will have names that resemble "W3wp#1" or "W3sp#2"and so on. This was remedied in .NET Framework 2.0 to include a counter named Process ID in the .NET CLR Memory performance object. This counter displays the process ID for an instance. You can use this counter to determine the CLR performance counter that is associated with a process.

Also KB 281884:

By default, Performance Monitor (Perfmon.msc) displays multiple processes that have the same name by enumerating the processes in the following way:

Process#1 Process#2 Process#3

Performance Monitor can also display these processes by appending the process ID (PID) to the name in the following way:

Process_PID

Answer 2

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;
        }
     }
  }
  throw new Exception("Could not find performance counter " + 
      "instance name for current process. This is truly strange ...");
}

Answer 3

The example by chiru does not work in a specific case - when you have two versions of the same program, named the same, and one is not .net and you start the .net version after the non-.net version. The .Net version will be named applicaion#1 but when you access the CLR perf counters using this name, the instance names on the counter has the name withouth the #1, so you get failures.

Nick.

Answer 4

Even though changing of registry settings look quite easy, unfortunately most of us dont have the rights to do it on the server (or we dont want to touch it!). In that case, there is a small workaround. I have blogged about this here.