It seems that we have some misunderstaning of swank:*globally-redirect-io* variable. Consider code shown below:
(setf swank:*globally-redirect-io* t) (setf swank:*use-dedicated-output-stream* nil) (swank:create-server :dont-close t) (threads:make-thread (lambda () (some-processing-function)))
When slime is connected to this program it does not receive any output (which goes to any of *standard-output*, *trace-output*, *debug-io*). The expected behaviour is output being redirected to slime connected.