+ # The maximum number of instances to run at a time, or 0 for
+ # unlimited.
+ #
+ # If more instances than this are already running and busy
+ # when the dispatcher starts up, the running containers will
+ # be allowed to finish before the excess instances are shut
+ # down.
+ MaxInstances: 64
+
+ # Maximum fraction of CloudVMs.MaxInstances allowed to run
+ # "supervisor" containers at any given time. A supervisor is a
+ # container whose purpose is mainly to submit and manage other
+ # containers, such as arvados-cwl-runner workflow runner.
+ #
+ # If there is a hard limit on the amount of concurrent
+ # containers that the cluster can run, it is important to
+ # avoid crowding out the containers doing useful work with
+ # containers who just create more work.
+ #
+ # For example, with the default MaxInstances of 64, it will
+ # schedule at most floor(64*0.30) = 19 concurrent workflows,
+ # ensuring 45 slots are available for work.
+ SupervisorFraction: 0.30
+