SQL Server 2017 how to detect if there are open connections?

SQL Server Administration
1

Hello guys,

I am load testing my rest API with JMeter. I got this error below when testing with 2500 users and 10 seconds ramp-up time. I wonder if there are any open connections that I can detect from SQL Server. Any ideas in order to get rid of this error?

System.InvalidOperationException: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
The underlying provider failed on Open.

Best Regards.

2

SQL Server will tell you the number of open connections and sessions by querying sys.dm_exec_sessions and sys.dm_exec_connections.

That error sounds like the connection pool in Java isn't big enough for 2500 connections.