SQL takes 100% of CPU despite low activity of the DB
An EC2 machine in AWS with SQL 2012, with 16 cores & 122 GB RAM.
The application layer consists of ~150 servers which hold a lot of connections (between 3 – 5 K during peak times).
At peak times for the application, my CPU constantly goes up to 100% (sql server engine process).
Using the sys.dm_exec_* DMVs & sp_whoisactive I see that the DB actually is not doing much – usually about 20 – 50 very fast queries (under 2 ms each).
The number of connections is indeed high, but even dropping most of the inactive ones has little to no effect on the matter.
At this point in time I don't have the ability to setup the environment to use fewer connections.
It's driving me nuts … any advise would be most welcome 🙂