1 ;;;; garbage collection and allocation-related code
3 ;;;; This software is part of the SBCL system. See the README file for
6 ;;;; This software is derived from the CMU CL system, which was
7 ;;;; written at Carnegie Mellon University and released into the
8 ;;;; public domain. The software is in the public domain and is
9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
10 ;;;; files for more information.
12 (in-package "SB!KERNEL")
14 ;;;; DYNAMIC-USAGE and friends
16 (declaim (special sb!vm:*read-only-space-free-pointer*
17 sb!vm:*static-space-free-pointer*))
19 (eval-when (:compile-toplevel :execute)
20 (sb!xc:defmacro def-c-var-frob (lisp-fun c-var-name)
22 #!-sb-fluid (declaim (inline ,lisp-fun))
24 (sb!alien:extern-alien ,c-var-name (sb!alien:unsigned 32))))))
26 #!-sb-fluid (declaim (inline dynamic-usage))
27 (def-c-var-frob dynamic-usage "bytes_allocated")
29 (defun static-space-usage ()
30 (- (* sb!vm:*static-space-free-pointer* sb!vm:word-bytes)
31 sb!vm:static-space-start))
33 (defun read-only-space-usage ()
34 (- (* sb!vm::*read-only-space-free-pointer* sb!vm:word-bytes)
35 sb!vm:read-only-space-start))
37 (defun control-stack-usage ()
38 #!-x86 (- (sb!sys:sap-int (sb!c::control-stack-pointer-sap))
39 sb!vm:control-stack-start)
40 #!+x86 (- sb!vm:control-stack-end
41 (sb!sys:sap-int (sb!c::control-stack-pointer-sap))))
43 (defun binding-stack-usage ()
44 (- (sb!sys:sap-int (sb!c::binding-stack-pointer-sap))
45 sb!vm:binding-stack-start))
49 (defun room-minimal-info ()
50 (format t "Dynamic space usage is: ~10:D bytes.~%" (dynamic-usage))
51 (format t "Read-only space usage is: ~10:D bytes.~%" (read-only-space-usage))
52 (format t "Static space usage is: ~10:D bytes.~%" (static-space-usage))
53 (format t "Control stack usage is: ~10:D bytes.~%" (control-stack-usage))
54 (format t "Binding stack usage is: ~10:D bytes.~%" (binding-stack-usage))
55 (format t "Garbage collection is currently ~:[enabled~;DISABLED~].~%"
58 (defun room-intermediate-info ()
60 (sb!vm:memory-usage :count-spaces '(:dynamic)
65 (defun room-maximal-info ()
67 (sb!vm:memory-usage :count-spaces '(:static :dynamic))
68 (sb!vm:instance-usage :dynamic :top-n 10)
69 (sb!vm:instance-usage :static :top-n 10))
71 (defun room (&optional (verbosity :default))
73 "Prints to *STANDARD-OUTPUT* information about the state of internal
74 storage and its management. The optional argument controls the
75 verbosity of ROOM. If it is T, ROOM prints out a maximal amount of
76 information. If it is NIL, ROOM prints out a minimal amount of
77 information. If it is :DEFAULT or it is not supplied, ROOM prints out
78 an intermediate amount of information. See also VM:MEMORY-USAGE and
79 VM:INSTANCE-USAGE for finer report control."
87 (room-intermediate-info)))
93 (defvar *last-bytes-in-use* nil)
94 (defvar *total-bytes-consed* 0)
95 (declaim (type (or index null) *last-bytes-in-use*))
96 (declaim (type integer *total-bytes-consed*))
98 (declaim (ftype (function () unsigned-byte) get-bytes-consed))
99 (defun get-bytes-consed ()
101 "Returns the number of bytes consed since the first time this function
102 was called. The first time it is called, it returns zero."
103 (declare (optimize (speed 3) (safety 0)))
104 (cond ((null *last-bytes-in-use*)
105 (setq *last-bytes-in-use* (dynamic-usage))
106 (setq *total-bytes-consed* 0))
108 (let ((bytes (dynamic-usage)))
109 (incf *total-bytes-consed*
110 (the index (- bytes *last-bytes-in-use*)))
111 (setq *last-bytes-in-use* bytes))))
112 *total-bytes-consed*)
114 ;;;; variables and constants
116 ;;; the default value of *BYTES-CONSED-BETWEEN-GCS* and *GC-TRIGGER*
117 (defconstant default-bytes-consed-between-gcs 2000000)
119 ;;; This variable is the user-settable variable that specifies the
120 ;;; minimum amount of dynamic space which must be consed before a GC
121 ;;; will be triggered.
123 ;;; Unlike CMU CL, we don't export this variable. (There's no need to, since
124 ;;; the BYTES-CONSED-BETWEEN-GCS function is SETFable.)
125 (defvar *bytes-consed-between-gcs* default-bytes-consed-between-gcs
127 "This number specifies the minimum number of bytes of dynamic space
128 that must be consed before the next GC will occur.")
129 (declaim (type index *bytes-consed-between-gcs*))
133 ;;; These variables are a list of functions which are run before and
134 ;;; after garbage collection occurs.
135 (defvar *before-gc-hooks* nil ; actually initialized in cold init
137 "A list of functions that are called before garbage collection occurs.
138 The functions should take no arguments.")
139 (defvar *after-gc-hooks* nil ; actually initialized in cold init
141 "A list of functions that are called after garbage collection occurs.
142 The functions should take no arguments.")
144 ;;; This hook is invoked whenever SUB-GC intends to GC (unless the GC
145 ;;; was explicitly forced by calling SB!EXT:GC). If the hook function
146 ;;; returns NIL then the GC procedes; otherwise, the GC is inhibited and
147 ;;; *GC-INHIBIT* and *NEED-TO-COLLECT-GARBAGE* are left bound to T.
148 ;;; Presumably someone will call GC-ON later to collect the garbage.
149 (defvar *gc-inhibit-hook* nil
151 "Should be bound to a function or NIL. If it is a function, this
152 function should take one argument, the current amount of dynamic
153 usage. The function should return NIL if garbage collection should
154 continue and non-NIL if it should be inhibited. Use with caution.")
156 (defvar *gc-verbose* nil ; (actually initialized in cold init)
158 "Should low-level GC functions produce verbose diagnostic output?")
160 (defvar *gc-notify-stream* nil ; (actually initialized in cold init)
162 "When non-NIL, this must be a STREAM; and the functions bound to
163 *GC-NOTIFY-BEFORE* and *GC-NOTIFY-AFTER* are called with the
164 STREAM value before and after a garbage collection occurs
167 (defvar *gc-run-time* 0
169 "The total CPU time spent doing garbage collection (as reported by
170 GET-INTERNAL-RUN-TIME.)")
171 (declaim (type index *gc-run-time*))
173 ;;; a limit to help catch programs which allocate too much memory,
174 ;;; since a hard heap overflow is so hard to recover from.
175 (declaim (type (or unsigned-byte null) *soft-heap-limit*))
176 (defvar *soft-heap-limit* nil)
178 ;;; Internal trigger. When the dynamic usage increases beyond this
179 ;;; amount, the system notes that a garbage collection needs to occur by
180 ;;; setting *NEED-TO-COLLECT-GARBAGE* to T. It starts out as NIL meaning
181 ;;; nobody has figured out what it should be yet.
182 (defvar *gc-trigger* nil)
184 (declaim (type (or index null) *gc-trigger*))
186 ;;; On the RT, we store the GC trigger in a ``static'' symbol instead of
187 ;;; letting magic C code handle it. It gets initialized by the startup
188 ;;; code. The X86 port defines this here because it uses the `ibmrt'
189 ;;; feature in the C code for allocation and binding stack access and
190 ;;; a lot of stuff wants this INTERNAL_GC_TRIGGER available as well.
192 (defvar sb!vm::*internal-gc-trigger*)
194 ;;;; The following specials are used to control when garbage collection
197 ;;; When non-NIL, inhibits garbage collection.
198 (defvar *gc-inhibit*) ; initialized in cold init
200 ;;; This flag is used to prevent recursive entry into the garbage
202 (defvar *already-maybe-gcing*) ; initialized in cold init
204 ;;; When T, indicates that the dynamic usage has exceeded the value
206 (defvar *need-to-collect-garbage* nil) ; initialized in cold init
208 (defun default-gc-notify-before (notify-stream bytes-in-use)
209 (declare (type stream notify-stream))
210 (format notify-stream
211 "~&; GC is beginning with ~:D bytes in use.~%"
213 (finish-output notify-stream))
214 (defparameter *gc-notify-before* #'default-gc-notify-before
216 "This function bound to this variable is invoked before GC'ing (unless
217 *GC-NOTIFY-STREAM* is NIL) with the value of *GC-NOTIFY-STREAM* and
218 current amount of dynamic usage (in bytes). It should notify the
219 user that the system is going to GC.")
221 (defun default-gc-notify-after (notify-stream
225 (declare (type stream notify-stream))
226 (format notify-stream
227 "~&; GC has finished with ~:D bytes in use (~:D bytes freed).~%"
230 (format notify-stream
231 "~&; The new GC trigger is ~:D bytes.~%"
233 (finish-output notify-stream))
234 (defparameter *gc-notify-after* #'default-gc-notify-after
236 "The function bound to this variable is invoked after GC'ing (unless
237 *GC-VERBOSE* is NIL) with the value of *GC-NOTIFY-STREAM*,
238 the amount of dynamic usage (in bytes) now free, the number of
239 bytes freed by the GC, and the new GC trigger threshold. The function
240 should notify the user that the system has finished GC'ing.")
244 (sb!alien:def-alien-routine collect-garbage sb!c-call:int
245 #!+gencgc (last-gen sb!c-call:int))
247 (sb!alien:def-alien-routine set-auto-gc-trigger sb!c-call:void
248 (dynamic-usage sb!c-call:unsigned-long))
250 (sb!alien:def-alien-routine clear-auto-gc-trigger sb!c-call:void)
252 ;;; This variable contains the function that does the real GC. This is
253 ;;; for low-level GC experimentation. Do not touch it if you do not
254 ;;; know what you are doing.
255 (defvar *internal-gc* #'collect-garbage)
259 ;;; Used to carefully invoke hooks.
260 (eval-when (:compile-toplevel :execute)
261 (sb!xc:defmacro carefully-funcall (function &rest args)
262 `(handler-case (funcall ,function ,@args)
264 (warn "(FUNCALL ~S~{ ~S~}) lost:~%~A" ',function ',args cond)
267 ;;; SUB-GC decides when and if to do a garbage collection. The
268 ;;; VERBOSE-P flag controls whether or not the notify functions are
269 ;;; called. The FORCE-P flags controls if a GC should occur even if
270 ;;; the dynamic usage is not greater than *GC-TRIGGER*.
272 ;;; For GENCGC all generations < GEN will be GC'ed.
274 ;;; FIXME: The VERBOSE-P stuff is no longer used.
275 (defun sub-gc (&key (verbose-p *gc-verbose*) force-p #!+gencgc (gen 0))
276 (/show0 "entering SUB-GC")
277 (unless *already-maybe-gcing*
278 (/show0 "not *ALREADY-MAYBE-GCING*")
279 (let* ((*already-maybe-gcing* t)
280 (start-time (get-internal-run-time))
281 (pre-gc-dyn-usage (dynamic-usage))
282 ;; Currently we only check *SOFT-HEAP-LIMIT* at GC time,
283 ;; not for every allocation. That makes it cheap to do,
284 ;; even if it is a little ugly.
285 (soft-heap-limit-exceeded? (and *soft-heap-limit*
288 (*soft-heap-limit* (if soft-heap-limit-exceeded?
290 *bytes-consed-between-gcs*)
292 (when soft-heap-limit-exceeded?
293 (cerror "Continue with GC."
294 "soft heap limit exceeded (temporary new limit=~D)"
296 (unless (integerp (symbol-value '*bytes-consed-between-gcs*))
297 ;; The noise w/ symbol-value above is to keep the compiler
298 ;; from optimizing the test away because of the type declaim
299 ;; for *bytes-consed-between-gcs*.
301 ;; FIXME: I'm inclined either to get rid of the DECLAIM or to
302 ;; trust it, instead of doing this weird hack. It's not
303 ;; particularly trustable, since (SETF
304 ;; *BYTES-CONSED-BETWEEN-GCS* 'SEVEN) works. But it's also not
305 ;; very nice to have the type of the variable specified in two
306 ;; places which can (and in CMU CL 2.4.8 did, INTEGER vs.
307 ;; INDEX) drift apart. So perhaps we should just add a note to
308 ;; the variable documentation for *BYTES-CONSED-BETWEEN-GCS*
309 ;; that it must be an INDEX, and remove the DECLAIM. Or we
310 ;; could make a SETFable (BYTES-CONSED-BETWEEN-GCS) function
311 ;; and enforce the typing that way. And in fact the SETFable
312 ;; function already exists, so all we need do is make the
313 ;; variable private, and then we can trust the DECLAIM.
314 (warn "The value of *BYTES-CONSED-BETWEEN-GCS*, ~S, is not an ~
315 integer. Resetting it to ~D."
316 *bytes-consed-between-gcs*
317 default-bytes-consed-between-gcs)
318 (setf *bytes-consed-between-gcs* default-bytes-consed-between-gcs))
319 (when (and *gc-trigger* (> pre-gc-dyn-usage *gc-trigger*))
320 (/show0 "setting *NEED-TO-COLLECT-GARBAGE* to T")
321 (setf *need-to-collect-garbage* t))
323 (and *need-to-collect-garbage* (not *gc-inhibit*)))
324 (/show0 "Evidently we ought to collect garbage..")
325 (when (and (not force-p)
327 (carefully-funcall *gc-inhibit-hook* pre-gc-dyn-usage))
328 (/show0 "..but we're inhibited.")
329 (setf *gc-inhibit* t)
330 (return-from sub-gc nil))
331 ;; KLUDGE: Wow, we really mask interrupts all the time we're
332 ;; collecting garbage? That seems like a long time.. -- WHN 19991129
334 ;; FIXME: We probably shouldn't do this evil thing to
335 ;; *STANDARD-OUTPUT* in a binding which is wrapped around
336 ;; calls to user-settable GC hook functions.
337 (let ((*standard-output* *terminal-io*))
338 (when *gc-notify-stream*
339 (/show0 "doing the *GC-NOTIFY-BEFORE* thing")
340 (if (streamp *gc-notify-stream*)
341 (carefully-funcall *gc-notify-before*
345 "*GC-NOTIFY-STREAM* is set, but not a STREAM -- ignored.")))
346 (dolist (hook *before-gc-hooks*)
347 (/show0 "doing a hook from *BEFORE-GC-HOOKS*")
348 (carefully-funcall hook))
350 (clear-auto-gc-trigger))
351 (/show0 "FUNCALLing *INTERNAL-GC*, one way or another")
352 #!-gencgc (funcall *internal-gc*)
353 ;; FIXME: This EQ test is pretty gross. Among its other
354 ;; nastinesses, it looks as though it could break if we
355 ;; recompile COLLECT-GARBAGE.
356 #!+gencgc (if (eq *internal-gc* #'collect-garbage)
357 (funcall *internal-gc* gen)
358 (funcall *internal-gc*))
359 (/show0 "back from FUNCALL to *INTERNAL-GC*")
360 (let* ((post-gc-dyn-usage (dynamic-usage))
361 (bytes-freed (- pre-gc-dyn-usage post-gc-dyn-usage)))
362 (/show0 "got (DYNAMIC-USAGE) and BYTES-FREED")
363 (when *last-bytes-in-use*
364 (/show0 "doing *LAST-BYTES-IN-USE* thing")
365 (incf *total-bytes-consed*
366 (- pre-gc-dyn-usage *last-bytes-in-use*))
367 (/show0 "setting *LAST-BYTES-IN-USE*")
368 (setq *last-bytes-in-use* post-gc-dyn-usage))
369 (/show0 "clearing *NEED-TO-COLLECT-GARBAGE*")
370 (setf *need-to-collect-garbage* nil)
371 (/show0 "calculating NEW-GC-TRIGGER")
372 (let ((new-gc-trigger (+ post-gc-dyn-usage
373 *bytes-consed-between-gcs*)))
374 (/show0 "setting *GC-TRIGGER*")
375 (setf *gc-trigger* new-gc-trigger))
376 (/show0 "calling SET-AUTO-GC-TRIGGER")
377 (set-auto-gc-trigger *gc-trigger*)
378 (dolist (hook *after-gc-hooks*)
379 (/show0 "doing a hook from *AFTER-GC--HOOKS*")
380 ;; FIXME: This hook should be called with the same
381 ;; kind of information as *GC-NOTIFY-AFTER*. In
382 ;; particular, it would be nice for the hook function
383 ;; to be able to adjust *GC-TRIGGER* intelligently to
384 ;; e.g. 108% of total memory usage.
385 (carefully-funcall hook))
386 (when *gc-notify-stream*
387 (/show0 "doing the *GC-NOTIFY-AFTER* thing")
388 (if (streamp *gc-notify-stream*)
389 (carefully-funcall *gc-notify-after*
395 "*GC-NOTIFY-STREAM* is set, but not a stream -- ignored.")))))
396 (/show0 "scrubbing control stack")
397 (scrub-control-stack)))
398 (/show0 "updating *GC-RUN-TIME*")
399 (incf *gc-run-time* (- (get-internal-run-time)
401 ;; FIXME: should probably return (VALUES), here and in RETURN-FROM
402 (/show0 "returning from tail of SUB-GC")
405 ;;; This routine is called by the allocation miscops to decide whether
406 ;;; a GC should occur. The argument, OBJECT, is the newly allocated
407 ;;; object which must be returned to the caller.
408 (defun maybe-gc (&optional object)
412 ;;; This is the user-advertised garbage collection function.
414 ;;; KLUDGE: GC shouldn't have different parameters depending on what
415 ;;; garbage collector we use. -- WHN 19991020
417 (defun gc (&optional (verbose-p *gc-verbose*))
419 "Initiates a garbage collection. VERBOSE-P controls
420 whether or not GC statistics are printed."
421 (sub-gc :verbose-p verbose-p :force-p t))
423 (defun gc (&key (verbose *gc-verbose*) (gen 0) (full nil))
425 "Initiates a garbage collection. VERBOSE controls whether or not GC
426 statistics are printed. GEN controls the number of generations to garbage
428 ;; FIXME: The bare 6 here (corresponding to a bare 6 in
429 ;; the gencgc.c sources) is nasty.
430 (sub-gc :verbose-p verbose :force-p t :gen (if full 6 gen)))
432 ;;;; auxiliary functions
434 (defun bytes-consed-between-gcs ()
436 "Return the amount of memory that will be allocated before the next garbage
437 collection is initiated. This can be set with SETF."
438 *bytes-consed-between-gcs*)
439 (defun (setf bytes-consed-between-gcs) (val)
440 ;; FIXME: Shouldn't this (and the DECLAIM for the underlying variable)
441 ;; be for a strictly positive number type, e.g.
442 ;; (AND (INTEGER 1) FIXNUM)?
443 (declare (type index val))
444 (let ((old *bytes-consed-between-gcs*))
445 (setf *bytes-consed-between-gcs* val)
447 (setf *gc-trigger* (+ *gc-trigger* (- val old)))
448 (cond ((<= (dynamic-usage) *gc-trigger*)
449 (clear-auto-gc-trigger)
450 (set-auto-gc-trigger *gc-trigger*))
452 (sb!sys:scrub-control-stack)
458 "Enables the garbage collector."
459 (setq *gc-inhibit* nil)
460 (when *need-to-collect-garbage*
466 "Disables the garbage collector."
467 (setq *gc-inhibit* t)
470 ;;;; initialization stuff
472 (defun gc-cold-init-or-reinit ()
474 (if (< *gc-trigger* (dynamic-usage))
476 (set-auto-gc-trigger *gc-trigger*))))