I am always using this script to find which queries are currently running on my SQL Server and which queries are running for a long time. This is valid for SQL Server 2005, 2008, 2012, 2016 and 2019 versions.
SELECT Q.TEXT, req.session_id, req.status, req.command, req.cpu_time, req.total_elapsed_time FROM sys.dm_exec_requests req CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS Q
Sometimes we may need to identify currently running expansive query and kill them by following command
Linux/Windows System and SQL Server Database Administrator with more than 4.5 years of experience in Linux Servers administration, Windows Administration, Network Administration, SQL Server Administration, MySQL Administration and SQL Programming.