This article addresses the differences between the max_connections configuration option and the concurrency_level configuration options and why they are important.

If you have Flux configured to run against any of our supported databases, Oracle, MySQL, Sybase, SQL Server, or DB2, then you will need to have these two options configured.

The max_connections configuration option is the maximum number of connections that Flux is allowed to have with your database at one time. The concurrency_level configuration option is the maximum number of threads of execution that may fire simultaneously in a Flux engine, where a "thread of execution" is an individual job or thread in a flow chart that you want to execute simultaneously.

Flux needs anywhere between three and five connections at any given time when connecting to a database for internal processes. If your configuration is trying to run more threads then it has connection for, you will notice performance issues. The best solution for this problem is to set the max_connections configuration option to a number that is five higher than the concurrency_level configuration option.

Here are some examples of configuring the max_connections and concurrency_level in both the Flux engine configuration (.fec) file as well as through the configuration Object in code.

MAX_CONNECTIONS=15
CONCURRENCY_LEVEL=10
 
config.setMaxConnecitons(15);
config.setConcurrencyLevel(10);