how to enumerate performance objects using ASP.net?

There is a Perfmon sample in MSDN entitled "PerfMon Sample: Demonstrates How to Monitor System Performance Using Performance Counters".  The sample is written in C#.

Thanks.  The article and help on MSDN seem to tell me how to get counters based on a CategoryName or performance object.
I would like to enumerate the list of performance objects (CategoryNames).  Any examples on how to do that?

PerformanceCounterCategory[] catList = PerformanceCounterCategory.GetCategories();
               Trace.WriteLine(catList.Length);
               foreach (PerformanceCounterCategory cat in catList)
               {
                    Trace.WriteLine(cat.CategoryName);
                    PerformanceCounter [] counters = cat.GetCounters();
                    foreach (PerformanceCounter counter in counters)
                    {
                         Trace.WriteLine("\t" + counter.CounterName);
                    }
               }

Thanks a lot.
Thanks to Naveen too but Azra helped first.

Would you happen to know what this error msg means?

"Counter is not single instance, an instance name needs to be specified"

I get that when i do a cat[i].GetCounters()
it only happens for certain categories.

thanks in advance.

Certain categories have multiple instances.  Call the GetInstanceNames method of the PerformanceCounterCategory object first to get all of the instances, and then alter your line to read:

cat[i].GetCounters(strInstance)

for each instance found for that category.

Yes thanks a lot.
But some categories do not return any instances info.
I am getting the following error for some:

"The IAS Authentication Clients category doesn't provide any instance information, no accurate data can be returned. "

Yes thanks a lot.
But some categories do not return any instances info.
I am getting the following error for some:

"The IAS Authentication Clients category doesn't provide any instance information, no accurate data can be returned. "

What happens if you just call GetCounters() on that particular category?

Hi,

I tried your suggestion and am getting the same error.
"The IAS Authentication Clients category doesn't provide any instance information, no accurate data can be returned"

thanks.

I guess that is something you should check for in your try...catch block.  Certain categories may not provide any information.

moloko,
The exceptions you are getting are perfectly normal and valid. You just can't enumerate the counters in a catagory like that. There is more to it. GetCounters only works if there is a single instance of a category. But there are categories that have multiple instances. For those you will always get ArguementExceptions if you call GetCOunters(). For example "Thread" category. Try calling GetCounters() for this one. You will get exception thrown. The reason is that there are lots of threads running in the system. And each thread is a separate instance. Although the category will remain same for Thread type, but instances are different. In that case you will have to call GetCOunters (myInstanceName) by providing the instance name as parameter.
For categories like "System", there are no multiple instances. So you can directly enumerate the counters.
You can experiement it yourself by instantiating "PerfMon" and then choose "System" category and the choose "Thread" category. You will see that in first case "Instances" list is empty and disabled. Whereas for Thread, the Instances list is populated with all threads currently  running in the system.

The way to enumerate counters and other info for multi instance categories is...
1. Call GetCOunters() within try/catch.
2. Catch the ArgumentException exception.
3. In this exception handler, call ReadCategoty method. This will return you InstanceDataCollectionCollection.
4. This collection contains list of InstanceDataCollection.
5. Enumerate each entry in this list. And each item conatains InstanceData objects. Use these objects to get instance names and counter values.

Following is small snippet of code that will demo all this..
***********************
private void GetCounterCategories()
          {
               PerformanceCounterCategory[] catList;
               try
               {
                    catList = PerformanceCounterCategory.GetCategories();
                    int iCatCount = catList.Length;
                    Trace.WriteLine("There are " + iCatCount.ToString() + " categories");
                   
                    foreach (PerformanceCounterCategory cat in catList)
                    {
                         Trace.WriteLine(cat.CategoryName);
                         try
                         {
                              PerformanceCounter[] counters = cat.GetCounters();
                         }
                         catch(ArgumentException ex)
                         {
                              Trace.WriteLine(ex.Message);
                              InstanceDataCollectionCollection col = cat.ReadCategory();
                              DumpInstanceDataCollectionCollection(col);
                         }
                    }
               }
               catch (Win32Exception ex)
               {
                    Trace.WriteLine(ex.Message);
               }
          }

          private void DumpInstanceDataCollectionCollection(InstanceDataCollectionCollection col)
          {
               ICollection keys = col.Keys;
               foreach (object key in keys)
               {
                    object val = col[key.ToString()];
                    Trace.WriteLine("\t" + key.ToString() + ":" + val.ToString());
                    if (val is InstanceDataCollection)
                    {
                         DumpInstanceDataCollection((InstanceDataCollection)val);
                    }
               }
          }

          private void DumpInstanceDataCollection(InstanceDataCollection col)
          {
               ICollection keys = col.Keys;
               foreach (object key in keys)
               {
                    object val = col[key.ToString()];
                    Trace.WriteLine("\t" + key.ToString() + ":" + val.ToString());
                    if (val is InstanceData)
                    {
                         DumpInstance((InstanceData)val);
                    }
               }
          }

          private void DumpInstance(InstanceData data)
          {
               Trace.WriteLine("Data: " + data.InstanceName);
          }
***********************

Hope it helps..

Naveen