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 #!+(or cgc gencgc) (progn
27 #!-sb-fluid (declaim (inline dynamic-usage))
28 (def-c-var-frob dynamic-usage "bytes_allocated"))
31 (defun dynamic-usage ()
32 (the (unsigned-byte 32)
33 (- (sb!sys:sap-int (sb!c::dynamic-space-free-pointer))
34 (current-dynamic-space-start))))
37 #!-sb-fluid (declaim (inline current-dynamic-space-start))
38 (def-c-var-frob current-dynamic-space-start "current_dynamic_space"))
40 (defun static-space-usage ()
41 (- (* sb!vm:*static-space-free-pointer* sb!vm:word-bytes)
42 sb!vm:static-space-start))
44 (defun read-only-space-usage ()
45 (- (* sb!vm::*read-only-space-free-pointer* sb!vm:word-bytes)
46 sb!vm:read-only-space-start))
48 (defun control-stack-usage ()
49 #!-x86 (- (sb!sys:sap-int (sb!c::control-stack-pointer-sap))
50 sb!vm:control-stack-start)
51 #!+x86 (- sb!vm:control-stack-end
52 (sb!sys:sap-int (sb!c::control-stack-pointer-sap))))
54 (defun binding-stack-usage ()
55 (- (sb!sys:sap-int (sb!c::binding-stack-pointer-sap))
56 sb!vm:binding-stack-start))
60 (defun room-minimal-info ()
61 (format t "Dynamic space usage is: ~10:D bytes.~%" (dynamic-usage))
62 (format t "Read-only space usage is: ~10:D bytes.~%" (read-only-space-usage))
63 (format t "Static space usage is: ~10:D bytes.~%" (static-space-usage))
64 (format t "Control stack usage is: ~10:D bytes.~%" (control-stack-usage))
65 (format t "Binding stack usage is: ~10:D bytes.~%" (binding-stack-usage))
66 (format t "Garbage collection is currently ~:[enabled~;DISABLED~].~%"
69 (defun room-intermediate-info ()
71 (sb!vm:memory-usage :count-spaces '(:dynamic)
76 (defun room-maximal-info ()
78 (sb!vm:memory-usage :count-spaces '(:static :dynamic))
79 (sb!vm:instance-usage :dynamic :top-n 10)
80 (sb!vm:instance-usage :static :top-n 10))
82 (defun room (&optional (verbosity :default))
84 "Prints to *STANDARD-OUTPUT* information about the state of internal
85 storage and its management. The optional argument controls the
86 verbosity of ROOM. If it is T, ROOM prints out a maximal amount of
87 information. If it is NIL, ROOM prints out a minimal amount of
88 information. If it is :DEFAULT or it is not supplied, ROOM prints out
89 an intermediate amount of information. See also VM:MEMORY-USAGE and
90 VM:INSTANCE-USAGE for finer report control."
98 (room-intermediate-info)))
101 ;;;; GET-BYTES-CONSED
104 (defvar *last-bytes-in-use* nil)
105 (defvar *total-bytes-consed* 0)
106 (declaim (type (or index null) *last-bytes-in-use*))
107 (declaim (type integer *total-bytes-consed*))
109 (declaim (ftype (function () unsigned-byte) get-bytes-consed))
110 (defun get-bytes-consed ()
112 "Returns the number of bytes consed since the first time this function
113 was called. The first time it is called, it returns zero."
114 (declare (optimize (speed 3) (safety 0)))
115 (cond ((null *last-bytes-in-use*)
116 (setq *last-bytes-in-use* (dynamic-usage))
117 (setq *total-bytes-consed* 0))
119 (let ((bytes (dynamic-usage)))
120 (incf *total-bytes-consed*
121 (the index (- bytes *last-bytes-in-use*)))
122 (setq *last-bytes-in-use* bytes))))
123 *total-bytes-consed*)
125 ;;;; variables and constants
127 ;;; the default value of *BYTES-CONSED-BETWEEN-GCS* and *GC-TRIGGER*
128 (defconstant default-bytes-consed-between-gcs 2000000)
130 ;;; This variable is the user-settable variable that specifies the
131 ;;; minimum amount of dynamic space which must be consed before a GC
132 ;;; will be triggered.
134 ;;; Unlike CMU CL, we don't export this variable. (There's no need to, since
135 ;;; the BYTES-CONSED-BETWEEN-GCS function is SETFable.)
136 (defvar *bytes-consed-between-gcs* default-bytes-consed-between-gcs
138 "This number specifies the minimum number of bytes of dynamic space
139 that must be consed before the next GC will occur.")
140 (declaim (type index *bytes-consed-between-gcs*))
144 ;;; These variables are a list of functions which are run before and
145 ;;; after garbage collection occurs.
146 (defvar *before-gc-hooks* nil ; actually initialized in cold init
148 "A list of functions that are called before garbage collection occurs.
149 The functions should take no arguments.")
150 (defvar *after-gc-hooks* nil ; actually initialized in cold init
152 "A list of functions that are called after garbage collection occurs.
153 The functions should take no arguments.")
155 ;;; This hook is invoked whenever SUB-GC intends to GC (unless the GC
156 ;;; was explicitly forced by calling SB!EXT:GC). If the hook function
157 ;;; returns NIL then the GC procedes; otherwise, the GC is inhibited and
158 ;;; *GC-INHIBIT* and *NEED-TO-COLLECT-GARBAGE* are left bound to T.
159 ;;; Presumably someone will call GC-ON later to collect the garbage.
160 (defvar *gc-inhibit-hook* nil
162 "Should be bound to a function or NIL. If it is a function, this
163 function should take one argument, the current amount of dynamic
164 usage. The function should return NIL if garbage collection should
165 continue and non-NIL if it should be inhibited. Use with caution.")
167 (defvar *gc-notify-stream* nil ; (actually initialized in cold init)
169 "When non-NIL, this must be a STREAM; and the functions bound to
170 *GC-NOTIFY-BEFORE* and *GC-NOTIFY-AFTER* are called with the
171 STREAM value before and after a garbage collection occurs
174 (defvar *gc-run-time* 0
176 "The total CPU time spent doing garbage collection (as reported by
177 GET-INTERNAL-RUN-TIME.)")
178 (declaim (type index *gc-run-time*))
180 ;;; a limit to help catch programs which allocate too much memory,
181 ;;; since a hard heap overflow is so hard to recover from.
182 (declaim (type (or unsigned-byte null) *soft-heap-limit*))
183 (defvar *soft-heap-limit* nil)
185 ;;; Internal trigger. When the dynamic usage increases beyond this
186 ;;; amount, the system notes that a garbage collection needs to occur by
187 ;;; setting *NEED-TO-COLLECT-GARBAGE* to T. It starts out as NIL meaning
188 ;;; nobody has figured out what it should be yet.
189 (defvar *gc-trigger* nil)
191 (declaim (type (or index null) *gc-trigger*))
193 ;;; On the RT, we store the GC trigger in a ``static'' symbol instead of
194 ;;; letting magic C code handle it. It gets initialized by the startup
195 ;;; code. The X86 port defines this here because it uses the `ibmrt'
196 ;;; feature in the C code for allocation and binding stack access and
197 ;;; a lot of stuff wants this INTERNAL_GC_TRIGGER available as well.
199 (defvar sb!vm::*internal-gc-trigger*)
201 ;;;; The following specials are used to control when garbage collection
204 ;;; When non-NIL, inhibits garbage collection.
205 (defvar *gc-inhibit*) ; initialized in cold init
207 ;;; This flag is used to prevent recursive entry into the garbage
209 (defvar *already-maybe-gcing*) ; initialized in cold init
211 ;;; When T, indicates that the dynamic usage has exceeded the value
213 (defvar *need-to-collect-garbage* nil) ; initialized in cold init
215 (defun default-gc-notify-before (notify-stream bytes-in-use)
216 (declare (type stream notify-stream))
217 (format notify-stream
218 "~&; GC is beginning with ~:D bytes in use.~%"
220 (finish-output notify-stream))
221 (defparameter *gc-notify-before* #'default-gc-notify-before
223 "This function bound to this variable is invoked before GC'ing (unless
224 *GC-NOTIFY-STREAM* is NIL) with the value of *GC-NOTIFY-STREAM* and
225 current amount of dynamic usage (in bytes). It should notify the
226 user that the system is going to GC.")
228 (defun default-gc-notify-after (notify-stream
232 (declare (type stream notify-stream))
233 (format notify-stream
234 "~&; GC has finished with ~:D bytes in use (~:D bytes freed).~%"
237 (format notify-stream
238 "~&; The new GC trigger is ~:D bytes.~%"
240 (finish-output notify-stream))
241 (defparameter *gc-notify-after* #'default-gc-notify-after
243 "The function bound to this variable is invoked after GC'ing with
244 the value of *GC-NOTIFY-STREAM*, the amount of dynamic usage (in
245 bytes) now free, the number of bytes freed by the GC, and the new GC
246 trigger threshold. The function should notify the user that the system
247 has finished GC'ing.")
251 (sb!alien:def-alien-routine collect-garbage sb!c-call:int
252 #!+gencgc (last-gen sb!c-call:int))
255 (sb!alien:def-alien-routine set-auto-gc-trigger sb!c-call:void
256 (dynamic-usage sb!c-call:unsigned-long))
258 (sb!alien:def-alien-routine clear-auto-gc-trigger sb!c-call:void)
260 ;;; This variable contains the function that does the real GC. This is
261 ;;; for low-level GC experimentation. Do not touch it if you do not
262 ;;; know what you are doing.
263 (defvar *internal-gc* #'collect-garbage)
267 ;;; Used to carefully invoke hooks.
268 (eval-when (:compile-toplevel :execute)
269 (sb!xc:defmacro carefully-funcall (function &rest args)
270 `(handler-case (funcall ,function ,@args)
272 (warn "(FUNCALL ~S~{ ~S~}) lost:~%~A" ',function ',args cond)
275 ;;; SUB-GC decides when and if to do a garbage collection.
276 ;;; The FORCE-P flags controls if a GC should occur even if
277 ;;; the dynamic usage is not greater than *GC-TRIGGER*.
279 ;;; For GENCGC all generations < GEN will be GC'ed.
281 (defun sub-gc (&key force-p (gen 0))
282 (/show0 "entering SUB-GC")
283 (unless *already-maybe-gcing*
284 (let* ((*already-maybe-gcing* t)
285 (start-time (get-internal-run-time))
286 (pre-gc-dyn-usage (dynamic-usage))
287 ;; Currently we only check *SOFT-HEAP-LIMIT* at GC time,
288 ;; not for every allocation. That makes it cheap to do,
289 ;; even if it is a little ugly.
290 (soft-heap-limit-exceeded? (and *soft-heap-limit*
293 (*soft-heap-limit* (if soft-heap-limit-exceeded?
295 *bytes-consed-between-gcs*)
297 (when soft-heap-limit-exceeded?
298 (cerror "Continue with GC."
299 "soft heap limit exceeded (temporary new limit=~D)"
301 (unless (integerp (symbol-value '*bytes-consed-between-gcs*))
302 ;; The noise w/ symbol-value above is to keep the compiler
303 ;; from optimizing the test away because of the type declaim
304 ;; for *bytes-consed-between-gcs*.
306 ;; FIXME: I'm inclined either to get rid of the DECLAIM or to
307 ;; trust it, instead of doing this weird hack. It's not
308 ;; particularly trustable, since (SETF
309 ;; *BYTES-CONSED-BETWEEN-GCS* 'SEVEN) works. But it's also not
310 ;; very nice to have the type of the variable specified in two
311 ;; places which can (and in CMU CL 2.4.8 did, INTEGER vs.
312 ;; INDEX) drift apart. So perhaps we should just add a note to
313 ;; the variable documentation for *BYTES-CONSED-BETWEEN-GCS*
314 ;; that it must be an INDEX, and remove the DECLAIM. Or we
315 ;; could make a SETFable (BYTES-CONSED-BETWEEN-GCS) function
316 ;; and enforce the typing that way. And in fact the SETFable
317 ;; function already exists, so all we need do is make the
318 ;; variable private, and then we can trust the DECLAIM.
319 (warn "The value of *BYTES-CONSED-BETWEEN-GCS*, ~S, is not an ~
320 integer. Resetting it to ~D."
321 *bytes-consed-between-gcs*
322 default-bytes-consed-between-gcs)
323 (setf *bytes-consed-between-gcs* default-bytes-consed-between-gcs))
324 (when (and *gc-trigger* (> pre-gc-dyn-usage *gc-trigger*))
325 (setf *need-to-collect-garbage* t))
327 (and *need-to-collect-garbage* (not *gc-inhibit*)))
328 (when (and (not force-p)
330 (carefully-funcall *gc-inhibit-hook* pre-gc-dyn-usage))
331 (setf *gc-inhibit* t)
332 (return-from sub-gc nil))
333 ;; KLUDGE: Wow, we really mask interrupts all the time we're
334 ;; collecting garbage? That seems like a long time.. -- WHN 19991129
336 ;; FIXME: We probably shouldn't do this evil thing to
337 ;; *STANDARD-OUTPUT* in a binding which is wrapped around
338 ;; calls to user-settable GC hook functions.
339 (let ((*standard-output* *terminal-io*))
340 (when *gc-notify-stream*
341 (if (streamp *gc-notify-stream*)
342 (carefully-funcall *gc-notify-before*
346 "*GC-NOTIFY-STREAM* is set, but not a STREAM -- ignored.")))
347 (dolist (hook *before-gc-hooks*)
348 (carefully-funcall hook))
350 (clear-auto-gc-trigger))
351 #!-gencgc (funcall *internal-gc*)
352 ;; FIXME: This EQ test is pretty gross. Among its other
353 ;; nastinesses, it looks as though it could break if we
354 ;; recompile COLLECT-GARBAGE.
355 #!+gencgc (if (eq *internal-gc* #'collect-garbage)
356 (funcall *internal-gc* gen)
357 (funcall *internal-gc*))
358 (let* ((post-gc-dyn-usage (dynamic-usage))
359 (bytes-freed (- pre-gc-dyn-usage post-gc-dyn-usage)))
360 (/show0 "got (DYNAMIC-USAGE) and BYTES-FREED")
361 (when *last-bytes-in-use*
362 (/show0 "doing *LAST-BYTES-IN-USE* thing")
363 (incf *total-bytes-consed*
364 (- pre-gc-dyn-usage *last-bytes-in-use*))
365 (/show0 "setting *LAST-BYTES-IN-USE*")
366 (setq *last-bytes-in-use* post-gc-dyn-usage))
367 (/show0 "clearing *NEED-TO-COLLECT-GARBAGE*")
368 (setf *need-to-collect-garbage* nil)
369 (/show0 "calculating NEW-GC-TRIGGER")
370 (let ((new-gc-trigger (+ post-gc-dyn-usage
371 *bytes-consed-between-gcs*)))
372 (/show0 "setting *GC-TRIGGER*")
373 (setf *gc-trigger* new-gc-trigger))
374 (/show0 "calling SET-AUTO-GC-TRIGGER")
375 (set-auto-gc-trigger *gc-trigger*)
376 (dolist (hook *after-gc-hooks*)
377 (/show0 "doing a hook from *AFTER-GC--HOOKS*")
378 ;; FIXME: This hook should be called with the same
379 ;; kind of information as *GC-NOTIFY-AFTER*. In
380 ;; particular, it would be nice for the hook function
381 ;; to be able to adjust *GC-TRIGGER* intelligently to
382 ;; e.g. 108% of total memory usage.
383 (carefully-funcall hook))
384 (when *gc-notify-stream*
385 (if (streamp *gc-notify-stream*)
386 (carefully-funcall *gc-notify-after*
392 "*GC-NOTIFY-STREAM* is set, but not a stream -- ignored.")))))
393 (scrub-control-stack))) ;XXX again? we did this from C ...
394 (incf *gc-run-time* (- (get-internal-run-time)
396 ;; FIXME: should probably return (VALUES), here and in RETURN-FROM
399 ;;; This routine is called by the allocation miscops to decide whether
400 ;;; a GC should occur. The argument, OBJECT, is the newly allocated
401 ;;; object which must be returned to the caller.
402 (defun maybe-gc (&optional object)
406 ;;; This is the user-advertised garbage collection function.
408 (defun gc (&key (gen 0) (full nil) &allow-other-keys)
409 #!+(and sb-doc gencgc)
410 "Initiates a garbage collection. GEN controls the number of generations to garbage collect"
411 #!+(and sb-doc (not gencgc))
412 "Initiates a garbage collection. GEN may be provided for compatibility, but is ignored"
413 (sub-gc :force-p t :gen (if full 6 gen)))
416 ;;;; auxiliary functions
418 (defun bytes-consed-between-gcs ()
420 "Return the amount of memory that will be allocated before the next garbage
421 collection is initiated. This can be set with SETF."
422 *bytes-consed-between-gcs*)
423 (defun (setf bytes-consed-between-gcs) (val)
424 ;; FIXME: Shouldn't this (and the DECLAIM for the underlying variable)
425 ;; be for a strictly positive number type, e.g.
426 ;; (AND (INTEGER 1) FIXNUM)?
427 (declare (type index val))
428 (let ((old *bytes-consed-between-gcs*))
429 (setf *bytes-consed-between-gcs* val)
431 (setf *gc-trigger* (+ *gc-trigger* (- val old)))
432 (cond ((<= (dynamic-usage) *gc-trigger*)
433 (clear-auto-gc-trigger)
434 (set-auto-gc-trigger *gc-trigger*))
436 (sb!sys:scrub-control-stack)
442 "Enables the garbage collector."
443 (setq *gc-inhibit* nil)
444 (when *need-to-collect-garbage*
450 "Disables the garbage collector."
451 (setq *gc-inhibit* t)
454 ;;;; initialization stuff
456 (defun gc-cold-init-or-reinit ()
458 (if (< *gc-trigger* (dynamic-usage))
460 (set-auto-gc-trigger *gc-trigger*))))