Hi, Is there an equivalent of java.lang.Thread.join() on the lisp side of things? I looked around in LispThread.java and threads.lisp, but I don't see anything obvious. I'd like to be able to write something like: (let ((threads (loop for i from 0 to 5 collect (make-thread #'(lambda() (format t "hey~%")))))) (mapc #'thread-join threads) (format t "is for horses~%")) I've attached a patch that implements this version of thread-join. It implements java semantics, this thread-join always returns nil. I guess java doesn't really have a way to return arbitrary values, but we easily do! I was thinking about hacking it up a bit more so that thread-join would return the value of the function passed to make-thread, e.g. so that (thread-join (make-thread #'(lambda () 1))) would return 1. But then it occurred to me that this functionality is probably already in there under a different name. So, how do you guys join your threads? Cheers, -david k. P.S. Are there any known thread safety issues with CLOS? I've been getting some weird MOP errors that I made go away by redefining slot-value such that it has to acquire a global lock before it can do anything. I assume that the problem is in my code: but the threads that are executing when I get the failures share no code (or variables), and every time the errors pop up slot-value is on the callstack someplace.