\f
;;;; DYNAMIC-USAGE and friends
-(declaim (special sb!vm:*read-only-space-free-pointer*
- sb!vm:*static-space-free-pointer*))
-
(eval-when (:compile-toplevel :execute)
(sb!xc:defmacro def-c-var-fun (lisp-fun c-var-name)
`(defun ,lisp-fun ()
(declaim (type unsigned-byte *n-bytes-freed-or-purified*))
(defvar *n-bytes-freed-or-purified* 0)
(defun gc-reinit ()
- (gc-on)
+ (setq *gc-inhibit* nil)
(gc)
(setf *n-bytes-freed-or-purified* 0
*gc-run-time* 0
;;; For GENCGC all generations < GEN will be GC'ed.
-(defvar *already-in-gc*
- (sb!thread:make-mutex :name "GC lock") "ID of thread running SUB-GC")
+(defvar *already-in-gc* (sb!thread:make-mutex :name "GC lock"))
;;; A unique GC id. This is supplied for code that needs to detect
;;; whether a GC has happened since some earlier point in time. For
(defvar *gc-epoch* (cons nil nil))
(defun sub-gc (&key (gen 0))
- (unless (eq sb!thread:*current-thread*
- (sb!thread:mutex-value *already-in-gc*))
- ;; With gencgc, unless *GC-PENDING* every allocation in this
- ;; function triggers another gc, potentially exceeding maximum
- ;; interrupt nesting. If *GC-INHIBIT* is not true, however,
- ;; there is no guarantee that we would ever check for pending
- ;; GC -- so in that case we must first disable interrupts, which
- ;; needs to be done for GC anyways...
- (cond (*gc-inhibit*
- (setf *gc-pending* t))
- (t
- (without-interrupts
- (setf *gc-pending* t)
- (sb!thread:with-mutex (*already-in-gc*)
- (let ((old-usage (dynamic-usage))
- (new-usage 0))
- (unsafe-clear-roots)
-
- (gc-stop-the-world)
- (let ((start-time (get-internal-run-time)))
- (collect-garbage gen)
- (setf *gc-epoch* (cons nil nil))
- (incf *gc-run-time*
- (- (get-internal-run-time) start-time)))
- (setf *gc-pending* nil
- new-usage (dynamic-usage))
- (gc-start-the-world)
-
- ;; In a multithreaded environment the other threads will
- ;; see *n-b-f-o-p* change a little late, but that's OK.
- (let ((freed (- old-usage new-usage)))
- ;; GENCGC occasionally reports negative here, but the
- ;; current belief is that it is part of the normal order
- ;; of things and not a bug.
- (when (plusp freed)
- (incf *n-bytes-freed-or-purified* freed))))))
-
- ;; Outside the mutex, interrupts enabled: these may cause
- ;; another GC. FIXME: it can potentially exceed maximum
- ;; interrupt nesting by triggering GCs.
+ (cond (*gc-inhibit*
+ (setf *gc-pending* t)
+ nil)
+ (t
+ (without-interrupts
+ (setf *gc-pending* :in-progress)
+ ;; Tricks to to prevent triggerring a recursive gc. This is
+ ;; like a WITHOUT-GCING inside the lock except that we
+ ;; cannot call MAYBE-HANDLE-PENDING-GC at the end, because
+ ;; that would lead to a recursive attempt on the lock. In
+ ;; case you are wondering, wrapping the lock in a
+ ;; WITHOUT-GCING would also deadlock. The
+ ;; *IN-WITHOUT-GCING* part is used to tell the runtime that
+ ;; it's ok to have a pending gc even though *GC-INHIBIT* is
+ ;; NIL.
;;
- ;; Can that be avoided by having the finalizers and hooks
- ;; run only from the outermost SUB-GC?
- ;;
- ;; KLUDGE: Don't run the hooks in GC's triggered by dying
- ;; threads, so that user-code never runs with
- ;; (thread-alive-p *current-thread*) => nil
- ;; The long-term solution will be to keep a separate thread
- ;; for finalizers and after-gc hooks.
- (when (sb!thread:thread-alive-p sb!thread:*current-thread*)
- (run-pending-finalizers)
- (call-hooks "after-GC" *after-gc-hooks* :on-error :warn))))))
+ ;; Now, if GET-MUTEX did not cons, that would be enough.
+ ;; Because it does, we need the :IN-PROGRESS bit above to
+ ;; tell the runtime not to trigger gcs.
+ (let ((sb!impl::*in-without-gcing* t)
+ (sb!impl::*deadline* nil)
+ (sb!impl::*deadline-seconds* nil))
+ (sb!thread:with-mutex (*already-in-gc*)
+ (let ((*gc-inhibit* t))
+ (let ((old-usage (dynamic-usage))
+ (new-usage 0))
+ (unsafe-clear-roots)
+ (gc-stop-the-world)
+ (let ((start-time (get-internal-run-time)))
+ (collect-garbage gen)
+ (setf *gc-epoch* (cons nil nil))
+ (incf *gc-run-time*
+ (- (get-internal-run-time) start-time)))
+ (setf *gc-pending* nil
+ new-usage (dynamic-usage))
+ #!+sb-thread
+ (assert (not *stop-for-gc-pending*))
+ (gc-start-the-world)
+ ;; In a multithreaded environment the other threads
+ ;; will see *n-b-f-o-p* change a little late, but
+ ;; that's OK.
+ (let ((freed (- old-usage new-usage)))
+ ;; GENCGC occasionally reports negative here, but
+ ;; the current belief is that it is part of the
+ ;; normal order of things and not a bug.
+ (when (plusp freed)
+ (incf *n-bytes-freed-or-purified* freed)))))))
+ ;; While holding the mutex we were protected from
+ ;; SIG_STOP_FOR_GC and recursive GCs. Now, in order to
+ ;; preserve the invariant (*GC-PENDING* ->
+ ;; pseudo-atomic-interrupted or *GC-INHIBIT*), let's check
+ ;; explicitly for a pending gc before interrupts are
+ ;; enabled again.
+ (maybe-handle-pending-gc))
+ t)))
+
+(defun post-gc ()
+ ;; Outside the mutex, interrupts may be enabled: these may cause
+ ;; another GC. FIXME: it can potentially exceed maximum interrupt
+ ;; nesting by triggering GCs.
+ ;;
+ ;; Can that be avoided by having the finalizers and hooks run only
+ ;; from the outermost SUB-GC? If the nested GCs happen in interrupt
+ ;; handlers that's not enough.
+ ;;
+ ;; KLUDGE: Don't run the hooks in GC's if:
+ ;;
+ ;; A) this thread is dying, so that user-code never runs with
+ ;; (thread-alive-p *current-thread*) => nil
+ ;;
+ ;; B) interrupts are disabled somewhere up the call chain since we
+ ;; don't want to run user code in such a case.
+ ;;
+ ;; The long-term solution will be to keep a separate thread for
+ ;; finalizers and after-gc hooks.
+ (when (sb!thread:thread-alive-p sb!thread:*current-thread*)
+ (when *allow-with-interrupts*
+ (with-interrupts
+ (run-pending-finalizers)
+ (call-hooks "after-GC" *after-gc-hooks* :on-error :warn)))))
;;; This is the user-advertised garbage collection function.
(defun gc (&key (gen 0) (full nil) &allow-other-keys)
#!+(and sb-doc (not gencgc))
"Initiate a garbage collection. GEN may be provided for compatibility with
generational garbage collectors, but is ignored in this implementation."
- (sub-gc :gen (if full 6 gen)))
+ (when (sub-gc :gen (if full 6 gen))
+ (post-gc)))
+
+(define-alien-routine scrub-control-stack sb!alien:void)
(defun unsafe-clear-roots ()
;; KLUDGE: Do things in an attempt to get rid of extra roots. Unsafe
(or #!+sb-thread *stop-for-gc-pending*
*gc-pending*))
(sb!unix::receive-pending-interrupt)))
-
-;;; These work both regardless of whether we're inside WITHOUT-GCING
-;;; or not.
-(defun gc-on ()
- #!+sb-doc
- "Enable the garbage collector."
- (setq *gc-inhibit* nil)
- (maybe-handle-pending-gc)
- nil)
-
-(defun gc-off ()
- #!+sb-doc
- "Disable the garbage collector."
- (setq *gc-inhibit* t)
- nil)