I am using marathon to launch docker containers across a cluster of slaves. Each slave has an attribute set such as region=us-east-1 or region=us-west-1 and so on. I created an application with the constraint: [["region", "GROUP_BY"]]. I would expect the containers to be placed evenly across boxes with this attribute, regardless of the number of containers I launch. Unfortunately, I am unable to run more than (the number of slaves + 1) tasks (despite having ample free memory and cpu). I was able to reproduce this using the CLUSTER constraint as well. Am I using the constraint feature incorrectly?