Reading the value of a performance counter on Windows with C# .NET

In this post we saw how to list all performance categories and the performance counters within each category. It’s equally straightforward to read the value of a performance counter. You’ll need at least the category and the name of the performance counter. If the counter is available in multiple instances then you’ll need to specify the instance name as well.

The following code will read the CPU usage and memory usage counters:

private static void ReadValuesOfPerformanceCounters()
	PerformanceCounter processorTimeCounter = new PerformanceCounter("Processor", "% Processor Time", "_Total");
	PerformanceCounter memoryUsage = new PerformanceCounter("Memory", "Available MBytes");			
	Console.WriteLine("CPU usage counter: ");
	Console.WriteLine("Category: {0}", processorTimeCounter.CategoryName);
	Console.WriteLine("Instance: {0}", processorTimeCounter.InstanceName);
	Console.WriteLine("Counter name: {0}", processorTimeCounter.CounterName);
	Console.WriteLine("Help text: {0}", processorTimeCounter.CounterHelp);
	Console.WriteLine("Memory usage counter: ");
	Console.WriteLine("Category: {0}", memoryUsage.CategoryName);
	Console.WriteLine("Counter name: {0}", memoryUsage.CounterName);
	Console.WriteLine("Help text: {0}", memoryUsage.CounterHelp);
	while (true)
		Console.WriteLine("CPU value: {0}", processorTimeCounter.NextValue());
		Console.WriteLine("Memory value: {0}", memoryUsage.NextValue());

Here’s an excerpt of the output:

Reading values of performance counters

You can view all posts related to Diagnostics here.

Getting notified by a Windows process change in C# .NET

In this post we saw an example of using the ManagementEventWatcher object and and EventQuery query. The SQL-like query was used to subscribe to a WMI – Windows Management Instrumentation – level event, namely a change in the status of a Windows service. I won’t repeat the explanation here again concerning the techniques used. So if this is new to you then consult that post, the code is very similar.

In this post we’ll see how to get notified by the creation of a new Windows process. This can be as simple as starting up Notepad. A Windows process is represented by the Win32_Process WMI class which will be used in the query. We’ll take a slightly different approach and use the WqlEventQuery object which derives from EventQuery.

Consider the following code:

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Getting notified by a Windows Service status change in C# .NET

The ManagementEventWatcher object in the System.Management namespace makes it possible to subscribe to events within the WMI – Windows Management Instrumentation – context. A change in the status of a Windows service is such an event and it’s possible to get notified when that happens.

We saw examples of WMI queries on this blog before – check the link below – and the ManagementEventWatcher object also requires an SQL-like query string. Consider the following function:

private static void RunManagementEventWatcherForWindowsServices()
	EventQuery eventQuery = new EventQuery();
	eventQuery.QueryString = "SELECT * FROM __InstanceModificationEvent within 2 WHERE targetinstance isa 'Win32_Service'";	
	ManagementEventWatcher demoWatcher = new ManagementEventWatcher(eventQuery);
	demoWatcher.Options.Timeout = new TimeSpan(1, 0, 0);
	Console.WriteLine("Perform the appropriate change in a Windows service according to your query");
	ManagementBaseObject nextEvent = demoWatcher.WaitForNextEvent();			
	ManagementBaseObject targetInstance = ((ManagementBaseObject)nextEvent["targetinstance"]);
	PropertyDataCollection props = targetInstance.Properties;
	foreach (PropertyData prop in props)
		Console.WriteLine("Property name: {0}, property value: {1}", prop.Name, prop.Value);


We declare the query within an EventQuery object. Windows services are of type “Win32_Service” hence the “where targetinstance isa ‘Win32_Service'” clause. “within 2” means that we want to be notified 2 seconds after the status change has been detected. A change event is represented by the __InstanceModificationEvent class. There are many similar WMI system classes. A creation event corresponds to the __InstanceCreationEvent class. So the query is simply saying that we want to know of any status change in any Windows service 2 seconds after the change.

The timeout option means that the ManagementEventWatcher object will wait for the specified amount of time for the event to occur. After this a timeout exception will be thrown so you’ll need to handle that.

In order to read the properties of the Windows service we need to go a level down to “targetinstance” and read the properties of that ManagementBaseObject. Otherwise the “nextEvent” object properties are not too informative.

Run this code, open the Windows services window and stop or pause any Windows service. I stopped the Tomcat7 service running on my PC and got the following Console output:

Stopping any service caught by event watcher

You can of course refine your query using the property names of the target instance. You can always check the property names on MSDN. E.g. if you open the above link to the Win32_Service object then you’ll see that it has a “state” and a “name” property. So in case you’ll want to know that a service name “Tomcat7” was stopped then you can have the following query:

eventQuery.QueryString = "SELECT * FROM __InstanceModificationEvent within 2 WHERE targetinstance isa 'Win32_Service' and targetinstance.state = 'Stopped' and = 'Tomcat7'";

In this case starting Tomcat7 won’t trigger the watcher. Neither will stopping any other Windows service. The event watcher will only react if a service names “Tomcat7” was stopped, i.e. the “Status” property of the target instance was set to “Stopped”.

You can view all posts related to Diagnostics here.

Creating a new performance counter on Windows with C# .NET

In this post we saw how to list all performance counter categories and the performance counters within each category available on Windows. The last time I checked there were a little more than 27500 counters and 148 categories available on my local PC. That’s quite a lot and will probably cover most diagnostic needs where performance counters are involved in a bottleneck investigation.

However, at times you might want to create your own performance counter. The System.Diagnostics library provides the necessary objects. Here’s how you can create a new performance counter category and a counter within that category:

string categoryName = "Football";
if (!PerformanceCounterCategory.Exists(categoryName))
	string firstCounterName = "Goals scored";
	string firstCounterHelp = "Goals scored live update";
	string categoryHelp = "Football related real time statistics";
	PerformanceCounterCategory customCategory = new PerformanceCounterCategory(categoryName);
	PerformanceCounterCategory.Create(categoryName, categoryHelp, PerformanceCounterCategoryType.SingleInstance, firstCounterName, firstCounterHelp);

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How to find various machine-level system information with C# .NET

The Environment class holds a range of properties that help you describe the system your app is running on. Here come some examples with inline comments:

//returns true on my PC as it is a 64-bit OS
bool is64BitOperatingSystem = Environment.Is64BitOperatingSystem;
//returns the machine name, in my case ANDRAS1
string machineName = Environment.MachineName;
//returns information about the operating system version, build, major, minor etc.
OperatingSystem os = Environment.OSVersion;
//returns the platform id as an enumeration, in my case it's Win32NT
PlatformID platform = os.Platform;			
//the currently installed service pack, Service Pack 1 in my case
string servicePack = os.ServicePack;
//the toString version of the OS, this is "Microsoft Windows NT 6.1.7601 Service Pack 1" on this PC
string version = os.VersionString;

//I have 4 processors on this PC
int processorCount = Environment.ProcessorCount;

//returns 2 logical drives: C: and D:
string[] logicalDrives = Environment.GetLogicalDrives();

//this is how to find all environmental variables of the system and iterate through them
IDictionary envVars = Environment.GetEnvironmentVariables();
foreach (string key in envVars.Keys)
	//e.g. the JAVA_HOME env.var is set to "C:\Progra~1\Java\jdk1.7.0_51\"
	Debug.WriteLine(string.Concat("key: ", key, ": ", envVars[key]));

//retrieve the current CLR version, in my case it's "4.0.30319.18444"
Version clrVersion = Environment.Version;

View all posts related to diagnostics here.

Finding all WMI class properties with .NET C#

In this post we saw how to enumerate all WMI – Windows Management Intrumentation – namespaces and classes. Then in this post we saw an example of querying the system to retrieve all local drives:

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Finding all WMI class names within a WMI namespace with .NET C#

In this post we saw an example of using WMI objects such as ConnectionOptions, ObjectQuery and ManagementObjectSearcher to enumerate all local drives on a computer. Recall the SQL-like query we used:

ObjectQuery objectQuery = new ObjectQuery("SELECT Size, Name FROM Win32_LogicalDisk where DriveType=3");

We’ll now see a technique to list all WMI classes within a WMI namespace. First we get hold of the WMI namespaces:

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