Question

I have a method in a web service I am writing that compiles a list of Performance Counter Categories,Instances, and Counters on that System. It builds a xml document and returns that. The first time the method is called after being published to the server, it takes about 17 seconds to get a result. Each time it is called after that, it takes 38 seconds. If I republish, the first time after that takes 17 seconds and then I am back at 38 seconds per a call.

    [WebMethod(Description="Returns the CounterList in XML Format")]
    public XmlDocument GetCounters()
    {
        XmlDocument CounterList = new XmlDocument();
        XmlElement root = CounterList.CreateElement("CounterList");
        PerformanceCounterCategory[] pcc = PerformanceCounterCategory.GetCategories();
        foreach (PerformanceCounterCategory cat in pcc)
        {
            XmlElement Category = CounterList.CreateElement("Category");
            XmlAttribute CatName = CounterList.CreateAttribute("Name");
            CatName.Value = cat.CategoryName;
            Category.Attributes.Append(CatName);
            String[] instances = cat.GetInstanceNames();
            PerformanceCounter[] pc;
            if (instances.Length > 0)
            {
                pc = cat.GetCounters(instances[0]);
                XmlElement Instances = CounterList.CreateElement("Instances");
                foreach (String instance in instances)
                {
                    XmlElement Instance = CounterList.CreateElement("Instance");
                    Instance.AppendChild(CounterList.CreateTextNode(instance));
                    Instances.AppendChild(Instance);
                }
                Category.AppendChild(Instances);
            }
            else
                pc = cat.GetCounters();

            XmlElement Counters = CounterList.CreateElement("Counters");
            foreach (PerformanceCounter counter in pc)
            {
                XmlElement Counter = CounterList.CreateElement("Counter");
                Counter.AppendChild(CounterList.CreateTextNode(counter.CounterName));
                Counters.AppendChild(Counter);
            }
            Category.AppendChild(Counters);
            root.AppendChild(Category);
        }
        CounterList.AppendChild(root);
        return CounterList;
    }

Answer 1

I would comment out this line:

PerformanceCounterCategory[] pcc = PerformanceCounterCategory.GetCategories();

and see if the symptom persists.

Note, I tried the code as a regular function and the first one took about 4 seconds, subsequent executions took about .2 seconds.