How do I identify the thread in application that takes 100% CPU usage in PerfMon?

Question

Trying to fine-tune/optimize my C# application. Been running PerfMon and I consistently get a spike of 100% on some operations. I can get the thread instance number from PerfMon but from Visual Studio 2015's thread window when debugging, how do I know which thread is the corresponding one?

Or am I going about it the wrong way? I want to find out the identity of the thread that's spiking in CPU usage from time to time. Thanks in advance SO!

Answer 1

For this I would use Process Explorer. The process properties (double click on a process to open) has a threads tab. This can be sorted by CPU or cycles, and has a button to snapshot the thread stack.

It will also make use of debug symbols to resolve the content of that stack.

This makes it much easier to identify what code a thread is running.

Another option would be PerfView from the Windows Debugging Tools: which gives even more data (but has a steeper learning curve).