sbcl no longer supports (sb-thread:current-thread-id). bryan d. o'connor <bryan@lunch.org>**20050830023327] openmcl-threads using semaphores. bryan d. o'connor <bryan@lunch.org>**20050901181244] allegro-threads using gates. bryan d. o'connor <bryan@lunch.org>**20050901235948 patch written by Dirk Gerrits.