Mon, 09 Aug 2010 05:41:05 -0700
6966222: G1: simplify TaskQueue overflow handling
Reviewed-by: tonyp, ysr
1 /*
2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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7 * published by the Free Software Foundation.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
25 // A G1RemSet provides ways of iterating over pointers into a selected
26 // collection set.
28 class G1CollectedHeap;
29 class CardTableModRefBarrierSet;
30 class HRInto_G1RemSet;
31 class ConcurrentG1Refine;
33 class G1RemSet: public CHeapObj {
34 protected:
35 G1CollectedHeap* _g1;
36 unsigned _conc_refine_cards;
37 size_t n_workers();
39 public:
40 G1RemSet(G1CollectedHeap* g1) :
41 _g1(g1), _conc_refine_cards(0)
42 {}
44 // Invoke "blk->do_oop" on all pointers into the CS in object in regions
45 // outside the CS (having invoked "blk->set_region" to set the "from"
46 // region correctly beforehand.) The "worker_i" param is for the
47 // parallel case where the number of the worker thread calling this
48 // function can be helpful in partitioning the work to be done. It
49 // should be the same as the "i" passed to the calling thread's
50 // work(i) function. In the sequential case this param will be ingored.
51 virtual void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
52 int worker_i) = 0;
54 // Prepare for and cleanup after an oops_into_collection_set_do
55 // call. Must call each of these once before and after (in sequential
56 // code) any threads call oops into collection set do. (This offers an
57 // opportunity to sequential setup and teardown of structures needed by a
58 // parallel iteration over the CS's RS.)
59 virtual void prepare_for_oops_into_collection_set_do() = 0;
60 virtual void cleanup_after_oops_into_collection_set_do() = 0;
62 // If "this" is of the given subtype, return "this", else "NULL".
63 virtual HRInto_G1RemSet* as_HRInto_G1RemSet() { return NULL; }
65 // Record, if necessary, the fact that *p (where "p" is in region "from",
66 // and is, a fortiori, required to be non-NULL) has changed to its new value.
67 virtual void write_ref(HeapRegion* from, oop* p) = 0;
68 virtual void write_ref(HeapRegion* from, narrowOop* p) = 0;
69 virtual void par_write_ref(HeapRegion* from, oop* p, int tid) = 0;
70 virtual void par_write_ref(HeapRegion* from, narrowOop* p, int tid) = 0;
72 // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
73 // or card, respectively, such that a region or card with a corresponding
74 // 0 bit contains no part of any live object. Eliminates any remembered
75 // set entries that correspond to dead heap ranges.
76 virtual void scrub(BitMap* region_bm, BitMap* card_bm) = 0;
77 // Like the above, but assumes is called in parallel: "worker_num" is the
78 // parallel thread id of the current thread, and "claim_val" is the
79 // value that should be used to claim heap regions.
80 virtual void scrub_par(BitMap* region_bm, BitMap* card_bm,
81 int worker_num, int claim_val) = 0;
83 // Refine the card corresponding to "card_ptr". If "sts" is non-NULL,
84 // join and leave around parts that must be atomic wrt GC. (NULL means
85 // being done at a safepoint.)
86 // With some implementations of this routine, when check_for_refs_into_cset
87 // is true, a true result may be returned if the given card contains oops
88 // that have references into the current collection set.
89 virtual bool concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
90 bool check_for_refs_into_cset) {
91 return false;
92 }
94 // Print any relevant summary info.
95 virtual void print_summary_info() {}
97 // Prepare remebered set for verification.
98 virtual void prepare_for_verify() {};
99 };
102 // The simplest possible G1RemSet: iterates over all objects in non-CS
103 // regions, searching for pointers into the CS.
104 class StupidG1RemSet: public G1RemSet {
105 public:
106 StupidG1RemSet(G1CollectedHeap* g1) : G1RemSet(g1) {}
108 void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
109 int worker_i);
111 void prepare_for_oops_into_collection_set_do() {}
112 void cleanup_after_oops_into_collection_set_do() {}
114 // Nothing is necessary in the version below.
115 void write_ref(HeapRegion* from, oop* p) {}
116 void write_ref(HeapRegion* from, narrowOop* p) {}
117 void par_write_ref(HeapRegion* from, oop* p, int tid) {}
118 void par_write_ref(HeapRegion* from, narrowOop* p, int tid) {}
120 void scrub(BitMap* region_bm, BitMap* card_bm) {}
121 void scrub_par(BitMap* region_bm, BitMap* card_bm,
122 int worker_num, int claim_val) {}
124 };
126 // A G1RemSet in which each heap region has a rem set that records the
127 // external heap references into it. Uses a mod ref bs to track updates,
128 // so that they can be used to update the individual region remsets.
130 class HRInto_G1RemSet: public G1RemSet {
131 protected:
132 enum SomePrivateConstants {
133 UpdateRStoMergeSync = 0,
134 MergeRStoDoDirtySync = 1,
135 DoDirtySync = 2,
136 LastSync = 3,
138 SeqTask = 0,
139 NumSeqTasks = 1
140 };
142 CardTableModRefBS* _ct_bs;
143 SubTasksDone* _seq_task;
144 G1CollectorPolicy* _g1p;
146 ConcurrentG1Refine* _cg1r;
148 size_t* _cards_scanned;
149 size_t _total_cards_scanned;
151 // _traversal_in_progress is "true" iff a traversal is in progress.
153 bool _traversal_in_progress;
154 void set_traversal(bool b) { _traversal_in_progress = b; }
156 // Used for caching the closure that is responsible for scanning
157 // references into the collection set.
158 OopsInHeapRegionClosure** _cset_rs_update_cl;
160 // The routine that performs the actual work of refining a dirty
161 // card.
162 // If check_for_refs_into_refs is true then a true result is returned
163 // if the card contains oops that have references into the current
164 // collection set.
165 bool concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,
166 bool check_for_refs_into_cset);
168 protected:
169 template <class T> void write_ref_nv(HeapRegion* from, T* p);
170 template <class T> void par_write_ref_nv(HeapRegion* from, T* p, int tid);
172 public:
173 // This is called to reset dual hash tables after the gc pause
174 // is finished and the initial hash table is no longer being
175 // scanned.
176 void cleanupHRRS();
178 HRInto_G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
179 ~HRInto_G1RemSet();
181 void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
182 int worker_i);
184 void prepare_for_oops_into_collection_set_do();
185 void cleanup_after_oops_into_collection_set_do();
186 void scanRS(OopsInHeapRegionClosure* oc, int worker_i);
187 template <class T> void scanNewRefsRS_work(OopsInHeapRegionClosure* oc, int worker_i);
188 void scanNewRefsRS(OopsInHeapRegionClosure* oc, int worker_i) {
189 if (UseCompressedOops) {
190 scanNewRefsRS_work<narrowOop>(oc, worker_i);
191 } else {
192 scanNewRefsRS_work<oop>(oc, worker_i);
193 }
194 }
195 void updateRS(DirtyCardQueue* into_cset_dcq, int worker_i);
196 HeapRegion* calculateStartRegion(int i);
198 HRInto_G1RemSet* as_HRInto_G1RemSet() { return this; }
200 CardTableModRefBS* ct_bs() { return _ct_bs; }
201 size_t cardsScanned() { return _total_cards_scanned; }
203 // Record, if necessary, the fact that *p (where "p" is in region "from",
204 // which is required to be non-NULL) has changed to a new non-NULL value.
205 // [Below the virtual version calls a non-virtual protected
206 // workhorse that is templatified for narrow vs wide oop.]
207 inline void write_ref(HeapRegion* from, oop* p) {
208 write_ref_nv(from, p);
209 }
210 inline void write_ref(HeapRegion* from, narrowOop* p) {
211 write_ref_nv(from, p);
212 }
213 inline void par_write_ref(HeapRegion* from, oop* p, int tid) {
214 par_write_ref_nv(from, p, tid);
215 }
216 inline void par_write_ref(HeapRegion* from, narrowOop* p, int tid) {
217 par_write_ref_nv(from, p, tid);
218 }
220 bool self_forwarded(oop obj);
222 void scrub(BitMap* region_bm, BitMap* card_bm);
223 void scrub_par(BitMap* region_bm, BitMap* card_bm,
224 int worker_num, int claim_val);
226 // If check_for_refs_into_cset is true then a true result is returned
227 // if the card contains oops that have references into the current
228 // collection set.
229 virtual bool concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
230 bool check_for_refs_into_cset);
232 virtual void print_summary_info();
233 virtual void prepare_for_verify();
234 };
236 #define G1_REM_SET_LOGGING 0
238 class CountNonCleanMemRegionClosure: public MemRegionClosure {
239 G1CollectedHeap* _g1;
240 int _n;
241 HeapWord* _start_first;
242 public:
243 CountNonCleanMemRegionClosure(G1CollectedHeap* g1) :
244 _g1(g1), _n(0), _start_first(NULL)
245 {}
246 void do_MemRegion(MemRegion mr);
247 int n() { return _n; };
248 HeapWord* start_first() { return _start_first; }
249 };
251 class UpdateRSOopClosure: public OopClosure {
252 HeapRegion* _from;
253 HRInto_G1RemSet* _rs;
254 int _worker_i;
256 template <class T> void do_oop_work(T* p);
258 public:
259 UpdateRSOopClosure(HRInto_G1RemSet* rs, int worker_i = 0) :
260 _from(NULL), _rs(rs), _worker_i(worker_i) {
261 guarantee(_rs != NULL, "Requires an HRIntoG1RemSet");
262 }
264 void set_from(HeapRegion* from) {
265 assert(from != NULL, "from region must be non-NULL");
266 _from = from;
267 }
269 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
270 virtual void do_oop(oop* p) { do_oop_work(p); }
272 // Override: this closure is idempotent.
273 // bool idempotent() { return true; }
274 bool apply_to_weak_ref_discovered_field() { return true; }
275 };
277 class UpdateRSetImmediate: public OopsInHeapRegionClosure {
278 private:
279 G1RemSet* _g1_rem_set;
281 template <class T> void do_oop_work(T* p);
282 public:
283 UpdateRSetImmediate(G1RemSet* rs) :
284 _g1_rem_set(rs) {}
286 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
287 virtual void do_oop( oop* p) { do_oop_work(p); }
288 };