1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)compactingPermGenGen.cpp 1.22 08/11/24 12:22:45 JVM"
3 #endif
4 /*
5 * Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 #include "incls/_precompiled.incl"
29 #include "incls/_compactingPermGenGen.cpp.incl"
30
31
32 // An ObjectClosure helper: Recursively adjust all pointers in an object
33 // and all objects by referenced it. Clear marks on objects in order to
34 // prevent visiting any object twice. This helper is used when the
35 // RedefineClasses() API has been called.
36
37 class AdjustSharedObjectClosure : public ObjectClosure {
38 public:
39 void do_object(oop obj) {
40 if (obj->is_shared_readwrite()) {
41 if (obj->mark()->is_marked()) {
42 obj->init_mark(); // Don't revisit this object.
43 obj->adjust_pointers(); // Adjust this object's references.
44 }
45 }
46 }
47 };
48
49
50 // An OopClosure helper: Recursively adjust all pointers in an object
51 // and all objects by referenced it. Clear marks on objects in order
52 // to prevent visiting any object twice.
53
54 class RecursiveAdjustSharedObjectClosure : public OopClosure {
55 public:
56 void do_oop(oop* o) {
57 oop obj = *o;
58 if (obj->is_shared_readwrite()) {
59 if (obj->mark()->is_marked()) {
60 obj->init_mark(); // Don't revisit this object.
61 obj->oop_iterate(this); // Recurse - adjust objects referenced.
62 obj->adjust_pointers(); // Adjust this object's references.
63
64 // Special case: if a class has a read-only constant pool,
65 // then the read-write objects referenced by the pool must
66 // have their marks reset.
67
68 if (obj->klass() == Universe::instanceKlassKlassObj()) {
69 instanceKlass* ik = instanceKlass::cast((klassOop)obj);
70 constantPoolOop cp = ik->constants();
71 if (cp->is_shared_readonly()) {
72 cp->oop_iterate(this);
73 }
74 }
75 }
76 }
77 };
78 };
79
80
81 // We need to go through all placeholders in the system dictionary and
82 // try to resolve them into shared classes. Other threads might be in
83 // the process of loading a shared class and have strong roots on
84 // their stack to the class without having added the class to the
85 // dictionary yet. This means the class will be marked during phase 1
86 // but will not be unmarked during the application of the
87 // RecursiveAdjustSharedObjectClosure to the SystemDictionary. Note
88 // that we must not call find_shared_class with non-read-only symbols
89 // as doing so can cause hash codes to be computed, destroying
90 // forwarding pointers.
91 class TraversePlaceholdersClosure : public OopClosure {
92 public:
93 void do_oop(oop* o) {
94 oop obj = *o;
95 if (obj->klass() == Universe::symbolKlassObj() &&
96 obj->is_shared_readonly()) {
97 symbolHandle sym((symbolOop) obj);
98 oop k = SystemDictionary::find_shared_class(sym);
99 if (k != NULL) {
100 RecursiveAdjustSharedObjectClosure clo;
101 clo.do_oop(&k);
102 }
103 }
104 }
105 };
106
107
108 void CompactingPermGenGen::initialize_performance_counters() {
109
110 const char* gen_name = "perm";
111
112 // Generation Counters - generation 2, 1 subspace
113 _gen_counters = new GenerationCounters(gen_name, 2, 1, &_virtual_space);
114
115 _space_counters = new CSpaceCounters(gen_name, 0,
116 _virtual_space.reserved_size(),
117 _the_space, _gen_counters);
118 }
119
120 void CompactingPermGenGen::update_counters() {
121 if (UsePerfData) {
122 _space_counters->update_all();
123 _gen_counters->update_all();
124 }
125 }
126
127
128 CompactingPermGenGen::CompactingPermGenGen(ReservedSpace rs,
129 ReservedSpace shared_rs,
130 size_t initial_byte_size,
131 int level, GenRemSet* remset,
132 ContiguousSpace* space,
133 PermanentGenerationSpec* spec_) :
134 OneContigSpaceCardGeneration(rs, initial_byte_size, MinPermHeapExpansion,
135 level, remset, space) {
136
137 set_spec(spec_);
138 if (!UseSharedSpaces && !DumpSharedSpaces) {
139 spec()->disable_sharing();
140 }
141
142 // Break virtual space into address ranges for all spaces.
143
144 if (spec()->enable_shared_spaces()) {
145 shared_end = (HeapWord*)(shared_rs.base() + shared_rs.size());
146 misccode_end = shared_end;
147 misccode_bottom = misccode_end - heap_word_size(spec()->misc_code_size());
148 miscdata_end = misccode_bottom;
149 miscdata_bottom = miscdata_end - heap_word_size(spec()->misc_data_size());
150 readwrite_end = miscdata_bottom;
151 readwrite_bottom =
152 readwrite_end - heap_word_size(spec()->read_write_size());
153 readonly_end = readwrite_bottom;
154 readonly_bottom =
155 readonly_end - heap_word_size(spec()->read_only_size());
156 shared_bottom = readonly_bottom;
157 unshared_end = shared_bottom;
158 assert((char*)shared_bottom == shared_rs.base(), "shared space mismatch");
159 } else {
160 shared_end = (HeapWord*)(rs.base() + rs.size());
161 misccode_end = shared_end;
162 misccode_bottom = shared_end;
163 miscdata_end = shared_end;
164 miscdata_bottom = shared_end;
165 readwrite_end = shared_end;
166 readwrite_bottom = shared_end;
167 readonly_end = shared_end;
168 readonly_bottom = shared_end;
169 shared_bottom = shared_end;
170 unshared_end = shared_bottom;
171 }
172 unshared_bottom = (HeapWord*) rs.base();
173
174 // Verify shared and unshared spaces adjacent.
175 assert((char*)shared_bottom == rs.base()+rs.size(), "shared space mismatch");
176 assert(unshared_end > unshared_bottom, "shared space mismatch");
177
178 // Split reserved memory into pieces.
179
180 ReservedSpace ro_rs = shared_rs.first_part(spec()->read_only_size(),
181 UseSharedSpaces);
182 ReservedSpace tmp_rs1 = shared_rs.last_part(spec()->read_only_size());
183 ReservedSpace rw_rs = tmp_rs1.first_part(spec()->read_write_size(),
184 UseSharedSpaces);
185 ReservedSpace tmp_rs2 = tmp_rs1.last_part(spec()->read_write_size());
186 ReservedSpace md_rs = tmp_rs2.first_part(spec()->misc_data_size(),
187 UseSharedSpaces);
188 ReservedSpace mc_rs = tmp_rs2.last_part(spec()->misc_data_size());
189
190 _shared_space_size = spec()->read_only_size()
191 + spec()->read_write_size()
192 + spec()->misc_data_size()
193 + spec()->misc_code_size();
194
195 // Allocate the unshared (default) space.
196 _the_space = new ContigPermSpace(_bts,
197 MemRegion(unshared_bottom, heap_word_size(initial_byte_size)));
198 if (_the_space == NULL)
199 vm_exit_during_initialization("Could not allocate an unshared"
200 " CompactingPermGen Space");
201
202 // Allocate shared spaces
203 if (spec()->enable_shared_spaces()) {
204
205 // If mapping a shared file, the space is not committed, don't
206 // mangle.
207 NOT_PRODUCT(bool old_ZapUnusedHeapArea = ZapUnusedHeapArea;)
208 NOT_PRODUCT(if (UseSharedSpaces) ZapUnusedHeapArea = false;)
209
210 // Commit the memory behind the shared spaces if dumping (not
211 // mapping).
212 if (DumpSharedSpaces) {
213 _ro_vs.initialize(ro_rs, spec()->read_only_size());
214 _rw_vs.initialize(rw_rs, spec()->read_write_size());
215 _md_vs.initialize(md_rs, spec()->misc_data_size());
216 _mc_vs.initialize(mc_rs, spec()->misc_code_size());
217 }
218
219 // Allocate the shared spaces.
220 _ro_bts = new BlockOffsetSharedArray(
221 MemRegion(readonly_bottom,
222 heap_word_size(spec()->read_only_size())),
223 heap_word_size(spec()->read_only_size()));
224 _ro_space = new OffsetTableContigSpace(_ro_bts,
225 MemRegion(readonly_bottom, readonly_end));
226 _rw_bts = new BlockOffsetSharedArray(
227 MemRegion(readwrite_bottom,
228 heap_word_size(spec()->read_write_size())),
229 heap_word_size(spec()->read_write_size()));
230 _rw_space = new OffsetTableContigSpace(_rw_bts,
231 MemRegion(readwrite_bottom, readwrite_end));
232
233 // Restore mangling flag.
234 NOT_PRODUCT(ZapUnusedHeapArea = old_ZapUnusedHeapArea;)
235
236 if (_ro_space == NULL || _rw_space == NULL)
237 vm_exit_during_initialization("Could not allocate a shared space");
238
239 // Cover both shared spaces entirely with cards.
240 _rs->resize_covered_region(MemRegion(readonly_bottom, readwrite_end));
241
242 if (UseSharedSpaces) {
243
244 // Map in the regions in the shared file.
245 FileMapInfo* mapinfo = FileMapInfo::current_info();
246 size_t image_alignment = mapinfo->alignment();
247 CollectedHeap* ch = Universe::heap();
248 if ((!mapinfo->map_space(ro, ro_rs, _ro_space)) ||
249 (!mapinfo->map_space(rw, rw_rs, _rw_space)) ||
250 (!mapinfo->map_space(md, md_rs, NULL)) ||
251 (!mapinfo->map_space(mc, mc_rs, NULL)) ||
252 // check the alignment constraints
253 (ch == NULL || ch->kind() != CollectedHeap::GenCollectedHeap ||
254 image_alignment !=
255 ((GenCollectedHeap*)ch)->gen_policy()->max_alignment())) {
256 // Base addresses didn't match; skip sharing, but continue
257 shared_rs.release();
258 spec()->disable_sharing();
259 // If -Xshare:on is specified, print out the error message and exit VM,
260 // otherwise, set UseSharedSpaces to false and continue.
261 if (RequireSharedSpaces) {
262 vm_exit_during_initialization("Unable to use shared archive.", NULL);
263 } else {
264 FLAG_SET_DEFAULT(UseSharedSpaces, false);
265 }
266
267 // Note: freeing the block offset array objects does not
268 // currently free up the underlying storage.
269 delete _ro_bts;
270 _ro_bts = NULL;
271 delete _ro_space;
272 _ro_space = NULL;
273 delete _rw_bts;
274 _rw_bts = NULL;
275 delete _rw_space;
276 _rw_space = NULL;
277 shared_end = (HeapWord*)(rs.base() + rs.size());
278 _rs->resize_covered_region(MemRegion(shared_bottom, shared_bottom));
279 }
280 }
281
282 // Reserved region includes shared spaces for oop.is_in_reserved().
283 _reserved.set_end(shared_end);
284
285 } else {
286 _ro_space = NULL;
287 _rw_space = NULL;
288 }
289 }
290
291
292 // Do a complete scan of the shared read write space to catch all
293 // objects which contain references to any younger generation. Forward
294 // the pointers. Avoid space_iterate, as actually visiting all the
295 // objects in the space will page in more objects than we need.
296 // Instead, use the system dictionary as strong roots into the read
297 // write space.
298 //
299 // If a RedefineClasses() call has been made, then we have to iterate
300 // over the entire shared read-write space in order to find all the
301 // objects that need to be forwarded. For example, it is possible for
302 // an nmethod to be found and marked in GC phase-1 only for the nmethod
303 // to be freed by the time we reach GC phase-3. The underlying method
304 // is still marked, but we can't (easily) find it in GC phase-3 so we
305 // blow up in GC phase-4. With RedefineClasses() we want replaced code
306 // (EMCP or obsolete) to go away (i.e., be collectible) once it is no
307 // longer being executed by any thread so we keep minimal attachments
308 // to the replaced code. However, we can't guarantee when those EMCP
309 // or obsolete methods will be collected so they may still be out there
310 // even after we've severed our minimal attachments.
311
312 void CompactingPermGenGen::pre_adjust_pointers() {
313 if (spec()->enable_shared_spaces()) {
314 if (JvmtiExport::has_redefined_a_class()) {
315 // RedefineClasses() requires a brute force approach
316 AdjustSharedObjectClosure blk;
317 rw_space()->object_iterate(&blk);
318 } else {
319 RecursiveAdjustSharedObjectClosure blk;
320 Universe::oops_do(&blk);
321 StringTable::oops_do(&blk);
322 SystemDictionary::always_strong_classes_do(&blk);
323 TraversePlaceholdersClosure tpc;
324 SystemDictionary::placeholders_do(&tpc);
325 }
326 }
327 }
328
329
330 #ifdef ASSERT
331 class VerifyMarksClearedClosure : public ObjectClosure {
332 public:
333 void do_object(oop obj) {
334 assert(SharedSkipVerify || !obj->mark()->is_marked(),
335 "Shared oop still marked?");
336 }
337 };
338 #endif
339
340
341 void CompactingPermGenGen::post_compact() {
342 #ifdef ASSERT
343 if (!SharedSkipVerify && spec()->enable_shared_spaces()) {
344 VerifyMarksClearedClosure blk;
345 rw_space()->object_iterate(&blk);
346 }
347 #endif
348 }
349
350
351 void CompactingPermGenGen::space_iterate(SpaceClosure* blk, bool usedOnly) {
352 OneContigSpaceCardGeneration::space_iterate(blk, usedOnly);
353 if (spec()->enable_shared_spaces()) {
354 #ifdef PRODUCT
355 // Making the rw_space walkable will page in the entire space, and
356 // is to be avoided. However, this is required for Verify options.
357 ShouldNotReachHere();
358 #endif
359
360 blk->do_space(ro_space());
361 blk->do_space(rw_space());
362 }
363 }
364
365
366 void CompactingPermGenGen::print_on(outputStream* st) const {
367 OneContigSpaceCardGeneration::print_on(st);
368 if (spec()->enable_shared_spaces()) {
369 st->print(" ro");
370 ro_space()->print_on(st);
371 st->print(" rw");
372 rw_space()->print_on(st);
373 } else {
374 st->print_cr("No shared spaces configured.");
375 }
376 }
377
378
379 // References from the perm gen to the younger generation objects may
380 // occur in static fields in Java classes or in constant pool references
381 // to String objects.
382
383 void CompactingPermGenGen::younger_refs_iterate(OopsInGenClosure* blk) {
384 OneContigSpaceCardGeneration::younger_refs_iterate(blk);
385 if (spec()->enable_shared_spaces()) {
386 blk->set_generation(this);
387 // ro_space has no younger gen refs.
388 _rs->younger_refs_in_space_iterate(rw_space(), blk);
389 blk->reset_generation();
390 }
391 }
392
393
394 // Shared spaces are addressed in pre_adjust_pointers.
395 void CompactingPermGenGen::adjust_pointers() {
396 the_space()->adjust_pointers();
397 }
398
399
400 void CompactingPermGenGen::compact() {
401 the_space()->compact();
402 }
403
404
405 size_t CompactingPermGenGen::contiguous_available() const {
406 // Don't include shared spaces.
407 return OneContigSpaceCardGeneration::contiguous_available()
408 - _shared_space_size;
409 }
410
411 size_t CompactingPermGenGen::max_capacity() const {
412 // Don't include shared spaces.
413 assert(UseSharedSpaces || (_shared_space_size == 0),
414 "If not used, the size of shared spaces should be 0");
415 return OneContigSpaceCardGeneration::max_capacity()
416 - _shared_space_size;
417 }
418
419
420
421 bool CompactingPermGenGen::grow_by(size_t bytes) {
422 // Don't allow _virtual_size to expand into shared spaces.
423 size_t max_bytes = _virtual_space.uncommitted_size() - _shared_space_size;
424 if (bytes > _shared_space_size) {
425 bytes = _shared_space_size;
426 }
427 return OneContigSpaceCardGeneration::grow_by(bytes);
428 }
429
430
431 void CompactingPermGenGen::grow_to_reserved() {
432 // Don't allow _virtual_size to expand into shared spaces.
433 if (_virtual_space.uncommitted_size() > _shared_space_size) {
434 size_t remaining_bytes =
435 _virtual_space.uncommitted_size() - _shared_space_size;
436 bool success = OneContigSpaceCardGeneration::grow_by(remaining_bytes);
437 DEBUG_ONLY(if (!success) warning("grow to reserved failed");)
438 }
439 }
440
441
442 // No young generation references, clear this generation's main space's
443 // card table entries. Do NOT clear the card table entries for the
444 // read-only space (always clear) or the read-write space (valuable
445 // information).
446
447 void CompactingPermGenGen::clear_remembered_set() {
448 _rs->clear(MemRegion(the_space()->bottom(), the_space()->end()));
449 }
450
451
452 // Objects in this generation's main space may have moved, invalidate
453 // that space's cards. Do NOT invalidate the card table entries for the
454 // read-only or read-write spaces, as those objects never move.
455
456 void CompactingPermGenGen::invalidate_remembered_set() {
457 _rs->invalidate(used_region());
458 }
459
460
461 void CompactingPermGenGen::verify(bool allow_dirty) {
462 the_space()->verify(allow_dirty);
463 if (!SharedSkipVerify && spec()->enable_shared_spaces()) {
464 ro_space()->verify(allow_dirty);
465 rw_space()->verify(allow_dirty);
466 }
467 }
468
469
470 HeapWord* CompactingPermGenGen::unshared_bottom;
471 HeapWord* CompactingPermGenGen::unshared_end;
472 HeapWord* CompactingPermGenGen::shared_bottom;
473 HeapWord* CompactingPermGenGen::shared_end;
474 HeapWord* CompactingPermGenGen::readonly_bottom;
475 HeapWord* CompactingPermGenGen::readonly_end;
476 HeapWord* CompactingPermGenGen::readwrite_bottom;
477 HeapWord* CompactingPermGenGen::readwrite_end;
478 HeapWord* CompactingPermGenGen::miscdata_bottom;
479 HeapWord* CompactingPermGenGen::miscdata_end;
480 HeapWord* CompactingPermGenGen::misccode_bottom;
481 HeapWord* CompactingPermGenGen::misccode_end;
482
483 // JVM/TI RedefineClasses() support:
484 bool CompactingPermGenGen::remap_shared_readonly_as_readwrite() {
485 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
486
487 if (UseSharedSpaces) {
488 // remap the shared readonly space to shared readwrite, private
489 FileMapInfo* mapinfo = FileMapInfo::current_info();
490 if (!mapinfo->remap_shared_readonly_as_readwrite()) {
491 return false;
492 }
493 }
494 return true;
495 }
496
497 void** CompactingPermGenGen::_vtbl_list;