High CPU Usage - from time to time

Normally my project use about 15 - 25 % of cpu. But sometimes it goes to 100% and stay there until I reset server.
It happend on version v7.9.12 (now updated to 7.9.13), I think there is issue with default scan class which execute now (after reset) in 70ms and when CPU is 100% it takes about 20 second.

How to find what what cause this High CPU usage ?

I Attach thread dump file and some screens:
IgnitionServerSzamotuly_thread_dump20191213-102022.txt (150.2 KB)

Download a thread dump the next time the CPU spikes - in your second screenshot, there’s a tag provider and a SQLBridge thread both consuming a lot of CPU, but without a thread dump it’s impossible to know what they’re trying to do.

Text file which I append is not thread dump ?

:man_facepalming: skipped right over it, sorry about that.

The bad news is, all it does is let me point fingers at MSSQL/their JDBC driver. You could try updating the JDBC driver, but all I can really tell you is that in that thread dump, all 5 sql bridge executor threads are waiting for SQL Server to deliver results, as are several store and forward threads, as is the tag provider thread.

I would definitely recommend getting in contact with support - if nothing else they can help guide you through the process of updating the JDBC driver, but there may also be other optimizations or things they can look at specific to your system.