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The parameter Max Service Discriminators is used by the broker to avoid unnecessary engine routing and to report its neediness for engines to the director. This parameter can be set via Manager Configuration | Engine and Clients | Engine Balancing | Max Service Discriminators on the Admin GUI. In the broker logs, you might see a message like:

Info: Maximum number of discriminators x is reached when collecting service level discriminators

If Max Service Discriminators is set to 0, engines from Broker A might be pulled onto Broker B, even though they are not qualified to run the service submitted to Broker B. Setting the parameter to a value greater than 0, will reduce unnecessary engines routing.

If the Max Service Discriminators is set to a very high value, reporting of balance data from the broker to director will take more time which will slow down the balancing. If balancing is slowed down to an unacceptable level, lower the value of the parameter.

How Max Service Discriminators setting works