ipython/ipython — pull request #5091 by chapmanb (2014-02-11 12:56:43+00:00)
Title: Provide logging messages in ipcluster log when engine or controllers fail to start

This is a logging/debugging improvement that writes out error tracebacks when controllers or engines fail to start from ipcluster. Previously these were silently ignored and the start process hangs without helpful messages. This is useful for debugging problems with custom controller or engine classes as well as general failures during submission.