EMMA uses port 47653 by default for the runtime controller. On startup, EMMA prints: The runtime controller can be used to remote control the code coverage collection. Not sure if a lot of people use this, though. I certainly don't. Or does IDEA itself depend on it? If not, maybe the runtime controller could be disabled by default, and be enabled by a property on the Code Coverage configuration tab? The controller is set by the property "rt.control", the default seems to be in emma.jar!/emma_default.properties with a true value. It can also be set on the VM parameters, for example "-Demma.rt.control=false". This would prevent issues like: IDEADEV-3526 IDEA-11280 TW-1792