- (when *already-in-gc* (return-from sub-gc nil))
- (setf *need-to-collect-garbage* t)
- (when (zerop *gc-inhibit*)
- (let ((*already-in-gc* t))
- (without-interrupts (collect-garbage gen))
- (incf *n-bytes-freed-or-purified*
- (max 0 (- pre-gc-dynamic-usage (dynamic-usage))))
- (setf *need-to-collect-garbage* nil))
- (scrub-control-stack))
- (values))
-
-
+ (let ((me (sb!thread:current-thread-id)))
+ (when (eql (sb!thread::mutex-value *already-in-gc*) me)
+ (return-from sub-gc nil))
+ (setf *need-to-collect-garbage* t)
+ (when (zerop *gc-inhibit*)
+ (loop
+ (sb!thread:with-mutex (*already-in-gc*)
+ (unless *need-to-collect-garbage* (return-from sub-gc nil))
+ (without-interrupts
+ (gc-stop-the-world)
+ (collect-garbage gen)
+ (incf *n-bytes-freed-or-purified*
+ (max 0 (- pre-gc-dynamic-usage (dynamic-usage))))
+ (scrub-control-stack)
+ (setf *need-to-collect-garbage* nil)
+ (dolist (h *after-gc-hooks*) (carefully-funcall h))
+ (gc-start-the-world))
+ (sb!thread::reap-dead-threads))))))