How to know if a gen full garbage collection has been triggered between two checkpoints?

Question

I am doing analysis on the time spend in a critical section of code.

//Take a timestamp before
var before = DateTime.UtcNow;

DoCriticalMethod();

//Take a timestamp after
var after = DateTime.UtcNow;

And sometime I have some values clearly higher than others.

I suspect that it is Garbage collection, so I want to correlate the high values with the fact that a Garbage collection occured during the process.

I tried this so far : I take the counter before :

//Take the number before
int gc2CountBefore = GC.CollectionCount(2);

...

//Take the number after
bool hasgc2occured = (GC.CollectionCount(2) - gc2CountBefore) != 0;

Am I doing it in the good way?

Answer 1

The "RegisterForFullGCNotification" method registers for a notification to be raised when the runtime senses that a full garbage collection is approaching. There are two parts to this notification: when the full garbage collection is approaching and when the full garbage collection has completed.

To determine when a notification has been raised, use the "WaitForFullGCApproach" and "WaitForFullGCComplete" methods. Typically, you use these methods in a while loop to continually obtain a "GCNotificationStatus" enumeration that shows the status of the notification.

The "WaitForFullGCApproach" and the "WaitForFullGCComplete" methods are designed to work together. Using one without the other can produce indeterminate results.

Answer 2

You can prevent your application from garbage collecting during a certain section:

Prevent .NET Garbage collection for short period of time

I'd try that, then profile your code repeatedly. If you don't see as much fluctuation, it might be GC causing it.