X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fgc.lisp;h=f3b961540ee68d6d41407664b2a1ec503f0cd584;hb=e9c546b14771ebe96447c3920a75e9e580f9075f;hp=95ff75c8e68bccf012dfcd6cf45a03de49e48422;hpb=3d11412f3458048039cd8fece1db2aa6511118dc;p=sbcl.git diff --git a/src/code/gc.lisp b/src/code/gc.lisp index 95ff75c..f3b9615 100644 --- a/src/code/gc.lisp +++ b/src/code/gc.lisp @@ -118,11 +118,14 @@ (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)) + (setf *n-bytes-freed-or-purified* 0 + *gc-run-time* 0 + ;; See comment in interr.lisp + *heap-exhausted-error-condition* (make-condition 'heap-exhausted-error))) -(declaim (ftype (function () unsigned-byte) get-bytes-consed)) +(declaim (ftype (sfunction () unsigned-byte) get-bytes-consed)) (defun get-bytes-consed () #!+sb-doc "Return the number of bytes consed since the program began. Typically @@ -137,8 +140,9 @@ and submit it as a patch." ;;;; GC hooks (defvar *after-gc-hooks* nil - "Called after each garbage collection. In a multithreaded -environment these hooks may run in any thread.") + "Called after each garbage collection, except for garbage collections +triggered during thread exits. In a multithreaded environment these hooks may +run in any thread.") ;;;; internal GC @@ -173,47 +177,91 @@ environment these hooks may run in any thread.") ;;; 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 +;;; example: +;;; +;;; (let ((epoch *gc-epoch*)) +;;; ... +;;; (unless (eql epoch *gc-epoch) +;;; ....)) +;;; +;;; This isn't just a fixnum counter since then we'd have theoretical +;;; problems when exactly 2^29 GCs happen between epoch +;;; comparisons. Unlikely, but the cost of using a cons instead is too +;;; small to measure. -- JES, 2007-09-30 +(declaim (type cons *gc-epoch*)) +(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. - (setq *gc-pending* t) - (unless *gc-inhibit* - (sb!thread:with-mutex (*already-in-gc*) - (let ((old-usage (dynamic-usage)) - (new-usage 0)) - (unsafe-clear-roots) - ;; We need to disable interrupts for GC, but we also want - ;; to run as little as possible without them. - (without-interrupts - (gc-stop-the-world) - (collect-garbage gen) - (setf *gc-pending* nil - new-usage (dynamic-usage)) - (gc-start-the-world)) - ;; Interrupts re-enabled, but still inside the mutex. - ;; 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, these may cause another GC. FIXME: it can - ;; potentially exceed maximum interrupt nesting by triggering - ;; GCs. - (run-pending-finalizers) - (dolist (hook *after-gc-hooks*) - (handler-case - (funcall hook) - (error (c) - (warn "Error calling after GC hook ~S:~% ~S" hook c))))))) + (cond (*gc-inhibit* + (setf *gc-pending* t)) + (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. + ;; + ;; 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!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)) + ;; Outside the mutex, interrupts 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? + ;; + ;; 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))))) ;;; This is the user-advertised garbage collection function. (defun gc (&key (gen 0) (full nil) &allow-other-keys) @@ -230,6 +278,9 @@ environment these hooks may run in any thread.") ;; as having these cons more then we have space left leads to huge ;; badness. (scrub-control-stack) + ;; Power cache of the bignum printer: drops overly large bignums and + ;; removes duplicate entries. + (scrub-power-cache) ;; FIXME: CTYPE-OF-CACHE-CLEAR isn't thread-safe. #!-sb-thread (ctype-of-cache-clear)) @@ -256,18 +307,3 @@ environment these hooks may run in any thread.") (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)