Data source profiles
With release 7.0, a new parameter is available on data source profiles called maxActive which can be used to limit the number of actively executing SQL queries for a specific data source. Once the maximum active limit is reached, the next requested render of a SQL macro using the specific data source returns an error message instead of trying to connect to the database. The message is something like:
Unable to process your request at this time. Try again later. The connection limit was reached for this data source.
This gives administrators a way to help manage database connections. This provides control over data source profiles similar to what is available for application server based data sources configured in server.xml.
Application server based data sources
Application server based data sources have various management parameters including maxActive and maxWait. See Tomcat JDBC Connection Pool.
If you need to further limit the number of connections used by SQL macros, then you can use maxActive data source profile setting to also control the application data source by referencing the application data source in the data source profile. For example, if myDS is an application defined data source, then the following data source profile would further restrict SQL macro connections:
|myDS||dataSource=myDS | maxActive = 10|