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-fun
(lisp-fun c-var-name
)
22 (sb!alien
:extern-alien
,c-var-name
(sb!alien
:unsigned
32)))))
25 (declaim (inline current-dynamic-space-start
))
27 (defun current-dynamic-space-start () sb
!vm
:dynamic-space-start
)
29 (def-c-var-fun current-dynamic-space-start
"current_dynamic_space")
32 (declaim (inline dynamic-usage
))
34 (def-c-var-fun dynamic-usage
"bytes_allocated")
36 (defun dynamic-usage ()
37 (the (unsigned-byte 32)
38 (- (sb!sys
:sap-int
(sb!c
::dynamic-space-free-pointer
))
39 (current-dynamic-space-start))))
41 (defun static-space-usage ()
42 (- (* sb
!vm
:*static-space-free-pointer
* sb
!vm
:n-word-bytes
)
43 sb
!vm
:static-space-start
))
45 (defun read-only-space-usage ()
46 (- (* sb
!vm
::*read-only-space-free-pointer
* sb
!vm
:n-word-bytes
)
47 sb
!vm
:read-only-space-start
))
49 (defun control-stack-usage ()
50 #!-stack-grows-downward-not-upward
51 (- (sb!sys
:sap-int
(sb!c
::control-stack-pointer-sap
))
52 (sb!sys
:sap-int
(sb!di
::descriptor-sap sb
!vm
:*control-stack-start
*)))
53 #!+stack-grows-downward-not-upward
54 (- (sb!sys
:sap-int
(sb!di
::descriptor-sap sb
!vm
:*control-stack-end
*))
55 (sb!sys
:sap-int
(sb!c
::control-stack-pointer-sap
))))
57 (defun binding-stack-usage ()
58 (- (sb!sys
:sap-int
(sb!c
::binding-stack-pointer-sap
))
59 (sb!sys
:sap-int
(sb!di
::descriptor-sap sb
!vm
:*binding-stack-start
*))))
63 (defun room-minimal-info ()
64 (format t
"Dynamic space usage is: ~10:D bytes.~%" (dynamic-usage))
65 (format t
"Read-only space usage is: ~10:D bytes.~%" (read-only-space-usage))
66 (format t
"Static space usage is: ~10:D bytes.~%" (static-space-usage))
67 (format t
"Control stack usage is: ~10:D bytes.~%" (control-stack-usage))
68 (format t
"Binding stack usage is: ~10:D bytes.~%" (binding-stack-usage))
71 "Control and binding stack usage is for the current thread only.~%")
72 (format t
"Garbage collection is currently ~:[enabled~;DISABLED~].~%"
75 (defun room-intermediate-info ()
77 (sb!vm
:memory-usage
:count-spaces
'(:dynamic
)
82 (defun room-maximal-info ()
83 ;; FIXME: SB!VM:INSTANCE-USAGE calls suppressed until bug 344 is fixed
84 (room-intermediate-info)
85 ;; old way, could be restored when bug 344 fixed:
86 ;;x (room-minimal-info)
87 ;;x (sb!vm:memory-usage :count-spaces '(:static :dynamic))
88 ;;x (sb!vm:instance-usage :dynamic :top-n 10)
89 ;;x (sb!vm:instance-usage :static :top-n 10)
92 (defun room (&optional
(verbosity :default
))
94 "Print to *STANDARD-OUTPUT* information about the state of internal
95 storage and its management. The optional argument controls the
96 verbosity of output. If it is T, ROOM prints out a maximal amount of
97 information. If it is NIL, ROOM prints out a minimal amount of
98 information. If it is :DEFAULT or it is not supplied, ROOM prints out
99 an intermediate amount of information."
107 (room-intermediate-info)))
110 ;;;; GET-BYTES-CONSED
112 ;;; the total number of bytes freed so far (including any freeing
113 ;;; which goes on in PURIFY)
115 ;;; (We save this so that we can calculate the total number of bytes
116 ;;; ever allocated by adding this to the number of bytes currently
117 ;;; allocated and never freed.)
118 (declaim (type unsigned-byte
*n-bytes-freed-or-purified
*))
119 (defvar *n-bytes-freed-or-purified
* 0)
123 (setf *n-bytes-freed-or-purified
* 0
125 ;; See comment in interr.lisp
126 *heap-exhausted-error-condition
* (make-condition 'heap-exhausted-error
)))
128 (declaim (ftype (function () unsigned-byte
) get-bytes-consed
))
129 (defun get-bytes-consed ()
131 "Return the number of bytes consed since the program began. Typically
132 this result will be a consed bignum, so if you have an application (e.g.
133 profiling) which can't tolerate the overhead of consing bignums, you'll
134 probably want either to hack in at a lower level (as the code in the
135 SB-PROFILE package does), or to design a more microefficient interface
136 and submit it as a patch."
138 *n-bytes-freed-or-purified
*))
142 (defvar *after-gc-hooks
* nil
143 "Called after each garbage collection, except for garbage collections
144 triggered during thread exits. In a multithreaded environment these hooks may
150 (sb!alien
:define-alien-routine collect-garbage sb
!alien
:int
151 (#!+gencgc last-gen
#!-gencgc ignore sb
!alien
:int
))
155 (sb!alien
:define-alien-routine gc-stop-the-world sb
!alien
:void
)
156 (sb!alien
:define-alien-routine gc-start-the-world sb
!alien
:void
))
159 (defun gc-stop-the-world ())
160 (defun gc-start-the-world ()))
165 ;;; SUB-GC does a garbage collection. This is called from three places:
166 ;;; (1) The C runtime will call here when it detects that we've consed
167 ;;; enough to exceed the gc trigger threshold. This is done in
168 ;;; alloc() for gencgc or interrupt_maybe_gc() for cheneygc
169 ;;; (2) The user may request a collection using GC, below
170 ;;; (3) At the end of a WITHOUT-GCING section, we are called if
171 ;;; *NEED-TO-COLLECT-GARBAGE* is true
173 ;;; This is different from the behaviour in 0.7 and earlier: it no
174 ;;; longer decides whether to GC based on thresholds. If you call
175 ;;; SUB-GC you will definitely get a GC either now or when the
176 ;;; WITHOUT-GCING is over
178 ;;; For GENCGC all generations < GEN will be GC'ed.
180 (defvar *already-in-gc
*
181 (sb!thread
:make-mutex
:name
"GC lock") "ID of thread running SUB-GC")
183 ;;; A unique GC id. This is supplied for code that needs to detect
184 ;;; whether a GC has happened since some earlier point in time. For
187 ;;; (let ((epoch *gc-epoch*))
189 ;;; (unless (eql epoch *gc-epoch)
192 ;;; This isn't just a fixnum counter since then we'd have theoretical
193 ;;; problems when exactly 2^29 GCs happen between epoch
194 ;;; comparisons. Unlikely, but the cost of using a cons instead is too
195 ;;; small to measure. -- JES, 2007-09-30
196 (declaim (type cons
*gc-epoch
*))
197 (defvar *gc-epoch
* (cons nil nil
))
199 (defun sub-gc (&key
(gen 0))
200 (unless (eq sb
!thread
:*current-thread
*
201 (sb!thread
:mutex-value
*already-in-gc
*))
202 ;; With gencgc, unless *GC-PENDING* every allocation in this
203 ;; function triggers another gc, potentially exceeding maximum
204 ;; interrupt nesting. If *GC-INHIBIT* is not true, however,
205 ;; there is no guarantee that we would ever check for pending
206 ;; GC -- so in that case we must first disable interrupts, which
207 ;; needs to be done for GC anyways...
209 (setf *gc-pending
* t
))
212 (setf *gc-pending
* t
)
213 (sb!thread
:with-mutex
(*already-in-gc
*)
214 (let ((old-usage (dynamic-usage))
219 (let ((start-time (get-internal-run-time)))
220 (collect-garbage gen
)
221 (setf *gc-epoch
* (cons nil nil
))
223 (- (get-internal-run-time) start-time
)))
224 (setf *gc-pending
* nil
225 new-usage
(dynamic-usage))
228 ;; In a multithreaded environment the other threads will
229 ;; see *n-b-f-o-p* change a little late, but that's OK.
230 (let ((freed (- old-usage new-usage
)))
231 ;; GENCGC occasionally reports negative here, but the
232 ;; current belief is that it is part of the normal order
233 ;; of things and not a bug.
235 (incf *n-bytes-freed-or-purified
* freed
))))))
237 ;; Outside the mutex, interrupts enabled: these may cause
238 ;; another GC. FIXME: it can potentially exceed maximum
239 ;; interrupt nesting by triggering GCs.
241 ;; Can that be avoided by having the finalizers and hooks
242 ;; run only from the outermost SUB-GC?
244 ;; KLUDGE: Don't run the hooks in GC's triggered by dying
245 ;; threads, so that user-code never runs with
246 ;; (thread-alive-p *current-thread*) => nil
247 ;; The long-term solution will be to keep a separate thread
248 ;; for finalizers and after-gc hooks.
249 (when (sb!thread
:thread-alive-p sb
!thread
:*current-thread
*)
250 (run-pending-finalizers)
251 (dolist (hook *after-gc-hooks
*)
254 (serious-condition (c)
255 (warn "Error calling after-GC hook ~S:~% ~A" hook c
)))))))))
257 ;;; This is the user-advertised garbage collection function.
258 (defun gc (&key
(gen 0) (full nil
) &allow-other-keys
)
259 #!+(and sb-doc gencgc
)
260 "Initiate a garbage collection. GEN controls the number of generations
262 #!+(and sb-doc
(not gencgc
))
263 "Initiate a garbage collection. GEN may be provided for compatibility with
264 generational garbage collectors, but is ignored in this implementation."
265 (sub-gc :gen
(if full
6 gen
)))
267 (defun unsafe-clear-roots ()
268 ;; KLUDGE: Do things in an attempt to get rid of extra roots. Unsafe
269 ;; as having these cons more then we have space left leads to huge
271 (scrub-control-stack)
272 ;; Power cache of the bignum printer: drops overly large bignums and
273 ;; removes duplicate entries.
275 ;; FIXME: CTYPE-OF-CACHE-CLEAR isn't thread-safe.
277 (ctype-of-cache-clear))
280 ;;;; auxiliary functions
282 (defun bytes-consed-between-gcs ()
284 "Return the amount of memory that will be allocated before the next garbage
285 collection is initiated. This can be set with SETF."
286 (sb!alien
:extern-alien
"bytes_consed_between_gcs"
287 (sb!alien
:unsigned
32)))
289 (defun (setf bytes-consed-between-gcs
) (val)
290 (declare (type index val
))
291 (setf (sb!alien
:extern-alien
"bytes_consed_between_gcs"
292 (sb!alien
:unsigned
32))
295 (declaim (inline maybe-handle-pending-gc
))
296 (defun maybe-handle-pending-gc ()
297 (when (and (not *gc-inhibit
*)
298 (or #!+sb-thread
*stop-for-gc-pending
*
300 (sb!unix
::receive-pending-interrupt
)))
302 ;;; These work both regardless of whether we're inside WITHOUT-GCING
306 "Enable the garbage collector."
307 (setq *gc-inhibit
* nil
)
308 (maybe-handle-pending-gc)
313 "Disable the garbage collector."
314 (setq *gc-inhibit
* t
)