I've made a bunch of updates to the openmcl implementation. Details in the ChangeLog, but to summarize - fixes to backtrace - improvements to edit-definition for methods particularly - updates to reflect current multiprocessing support - support for slime-who-calls and friends via openmcl's recently added xref facility - support profiling in mcl (via metering.lisp) - define openmcl-set-debug-switches as place to put all those variables that control recording debug information. Now the kernel issue, which is present when running under OS X, but not linux. The problem manifests as the assertion in swank-backend::receive occasionally failing, hosing slime, typically during some long task. The cause was that a wait on semaphore that was returning when it shouldn't have (no signal). The fix should appear in the cvs soon, Gary Byers says (Gary found the fix, of course). If you want to patch it yourself the change is in lisp-kernel/thread_manager.c in the function wait_on_semaphore. Change if ((seconds <= 0) && (nanos <= 0)) { return 0 ; to if ((seconds <= 0) && (nanos <= 0)) { return KERN_OPERATION_TIMED_OUT ; Then cd to lisp-kernel/darwin/ and "make" Let me know if I've broken anything. BTW, congrats on slime 1.0, and sorry I couldn't get the changes in before the release. Blame it on 4 month old Jarrett Sagan Ruttenberg. -Alan