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Monitor your application using Event Counters–Part I

I’m building a data pipeline using TPL Dataflow to migrate data from a database to an external API. As this data pipeline could run for a long time, I was looking for a good way to monitor the progress. This turned out to be a perfect use case for Event Counters.

What are EventCounters?

Here is what the documentation has to say about Event Counters:

EventCounters are .NET APIs used for lightweight, cross-platform, and near real-time performance metric collection. EventCounters were added as a cross-platform alternative to the "performance counters" of .NET Framework on Windows. EventCounters can be used to track various metrics.

And somewhat further in the documentation:

Apart from the EventCounters that are provided by the .NET runtime, you may choose to implement your own EventCounters.

And that is exactly what we are going to do!

Implement our first EventCounter

There are 4 types of counters that you can use each with their own characteristics and use cases:

We’ll start with a simple use case; with our first EventCounter we want to track the number of records that are migrated. So this should be an ever increasing number while the migration pipeline is running.

  • I start by creating a class that inherits from EventSource:
  • Next, we need to annotate this class with the [EventSource] attribute and specify a unique name:
  • We foresee a static instance of our class and a variable that can be used to track the number of migrated records:
  • For this use case, I start by using the PollingCounter and keep track of the value ourself. We create a new instance of the PollingCounter and foresee a callback method that will be used to read the counted value.
    • Notice that we are using Interlocked.Read() to guarantee thread-safety.
  • As we want to track the value ourself, we also need to provide a method to update the count.
    • Again, we are using an Interlocked.Add() to guarantee thread-safety.

This is what the end result looks like (I added some extra cleanup logic):

In the next post, we’ll have a look how we can consume the EventCounters data using some of the dotnet tools.

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