Using Event Counters with Application Insights

When adding the Application Insights SDK to your application, a set of Performance Counters is tracked by default.

This is the list of default counters for ASP.NET web applications:

• % Process\Processor Time
• % Process\Processor Time Normalized
• Memory\Available Bytes
• ASP.NET Requests/Sec
• .NET CLR Exceptions Thrown / sec
• ASP.NET ApplicationsRequest Execution Time
• Process\Private Bytes
• Process\IO Data Bytes/sec
• ASP.NET Applications\Requests In Application Queue
• Processor(_Total)\% Processor Time

However Performance Counters are a windows only feature. With .NET being cross-platform, is there a solution that works on both Windows and Linux?

Of course there is! (Otherwise I wouldn’t be writing this blog post).

Collecting EventCounters with Application Insights

The documentation has the following to say about EventCounters:

EventCounter is .NET/.NET Core mechanism to publish and consume counters or statistics. EventCounters are supported in all OS platforms - Windows, Linux, and macOS. It can be thought of as a cross-platform equivalent for the PerformanceCounters that is only supported in Windows systems.

By default no EventCounters are collected, but they are easy to add by configuring the EventCounterCollectionModule:

	//Add event counters
	builder.Services.ConfigureTelemetryModule<EventCounterCollectionModule>(
	(module, o) =>
	{
	// This removes all default counters, if any.
	module.Counters.Clear();
	module.Counters.Add(new EventCounterCollectionRequest("System.Runtime", "gen-0-size"));
	module.Counters.Add(new EventCounterCollectionRequest("System.Runtime", "alloc-rate"));
	module.Counters.Add(new EventCounterCollectionRequest("System.Runtime", "cpu-usage"));
	module.Counters.Add(new EventCounterCollectionRequest("System.Runtime", "exception-count"));
	}
	);

view raw ConfigureTelemetry.cs hosted with ❤ by GitHub

Probably the hardest thing when implementing EventCounters is finding the list of built-in counters.

Here is an example where I added some extra EventCounters from ASP.NET Core:

Viewing EventCounters data in Application Insights

To view the tracked EventCounters, you need to look at the ‘Custom’ category inside the Log-based metrics namespace: