1 /*
2 * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
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,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classListParser.hpp"
27 #include "classfile/classLoaderExt.hpp"
28 #include "classfile/dictionary.hpp"
29 #include "classfile/loaderConstraints.hpp"
30 #include "classfile/placeholders.hpp"
31 #include "classfile/sharedClassUtil.hpp"
32 #include "classfile/symbolTable.hpp"
33 #include "classfile/systemDictionary.hpp"
34 #include "classfile/systemDictionaryShared.hpp"
35 #include "code/codeCache.hpp"
36 #include "gc/shared/gcLocker.hpp"
37 #include "interpreter/bytecodeStream.hpp"
38 #include "interpreter/bytecodes.hpp"
39 #include "logging/log.hpp"
40 #include "logging/logMessage.hpp"
41 #include "memory/filemap.hpp"
42 #include "memory/metaspace.hpp"
43 #include "memory/metaspaceShared.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "oops/instanceClassLoaderKlass.hpp"
46 #include "oops/instanceMirrorKlass.hpp"
47 #include "oops/instanceRefKlass.hpp"
48 #include "oops/objArrayKlass.hpp"
49 #include "oops/objArrayOop.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/typeArrayKlass.hpp"
52 #include "prims/jvm.h"
53 #include "prims/jvmtiRedefineClasses.hpp"
54 #include "runtime/timerTrace.hpp"
55 #include "runtime/os.hpp"
56 #include "runtime/signature.hpp"
57 #include "runtime/vmThread.hpp"
58 #include "runtime/vm_operations.hpp"
59 #include "utilities/align.hpp"
60 #include "utilities/defaultStream.hpp"
61 #include "utilities/hashtable.inline.hpp"
62 #include "memory/metaspaceClosure.hpp"
63
64 ReservedSpace MetaspaceShared::_shared_rs;
65 VirtualSpace MetaspaceShared::_shared_vs;
66 MetaspaceSharedStats MetaspaceShared::_stats;
67 bool MetaspaceShared::_has_error_classes;
68 bool MetaspaceShared::_archive_loading_failed = false;
69 bool MetaspaceShared::_remapped_readwrite = false;
70 address MetaspaceShared::_cds_i2i_entry_code_buffers = NULL;
71 size_t MetaspaceShared::_cds_i2i_entry_code_buffers_size = 0;
72 size_t MetaspaceShared::_core_spaces_size = 0;
73
74 // The CDS archive is divided into the following regions:
75 // mc - misc code (the method entry trampolines)
76 // rw - read-write metadata
77 // ro - read-only metadata and read-only tables
78 // md - misc data (the c++ vtables)
79 // od - optional data (original class files)
80 //
81 // s0 - shared strings #0
82 // s1 - shared strings #1 (may be empty)
83 //
84 // Except for the s0/s1 regions, the other 5 regions are linearly allocated, starting from
85 // SharedBaseAddress, in the order of mc->rw->ro->md->od. The size of these 5 regions
86 // are page-aligned, and there's no gap between any consecutive regions.
87 //
88 // These 5 regions are populated in the following steps:
89 // [1] All classes are loaded in MetaspaceShared::preload_classes(). All metadata are
90 // temporarily allocated outside of the shared regions. Only the method entry
91 // trampolines are written into the mc region.
92 // [2] ArchiveCompactor copies RW metadata into the rw region.
93 // [3] ArchiveCompactor copies RO metadata into the ro region.
94 // [4] SymbolTable, StringTable, SystemDictionary, and a few other read-only data
95 // are copied into the ro region as read-only tables.
96 // [5] C++ vtables are copied into the md region.
97 // [6] Original class files are copied into the od region.
98 //
99 // The s0/s1 regions are populated inside MetaspaceShared::dump_string_and_symbols. Their
100 // layout is independent of the other 5 regions.
101
102 class DumpRegion {
103 private:
104 const char* _name;
105 char* _base;
106 char* _top;
107 char* _end;
108 bool _is_packed;
109
110 char* expand_top_to(char* newtop) {
111 assert(is_allocatable(), "must be initialized and not packed");
112 assert(newtop >= _top, "must not grow backwards");
113 if (newtop > _end) {
114 MetaspaceShared::report_out_of_space(_name, newtop - _top);
115 ShouldNotReachHere();
116 }
117 MetaspaceShared::commit_shared_space_to(newtop);
118 _top = newtop;
119 return _top;
120 }
121
122 public:
123 DumpRegion(const char* name) : _name(name), _base(NULL), _top(NULL), _end(NULL), _is_packed(false) {}
124
125 char* allocate(size_t num_bytes, size_t alignment=BytesPerWord) {
126 char* p = (char*)align_up(_top, alignment);
127 char* newtop = p + align_up(num_bytes, alignment);
128 expand_top_to(newtop);
129 memset(p, 0, newtop - p);
130 return p;
131 }
132
133 void append_intptr_t(intptr_t n) {
134 assert(is_aligned(_top, sizeof(intptr_t)), "bad alignment");
135 intptr_t *p = (intptr_t*)_top;
136 char* newtop = _top + sizeof(intptr_t);
137 expand_top_to(newtop);
138 *p = n;
139 }
140
141 char* base() const { return _base; }
142 char* top() const { return _top; }
143 char* end() const { return _end; }
144 size_t reserved() const { return _end - _base; }
145 size_t used() const { return _top - _base; }
146 bool is_packed() const { return _is_packed; }
147 bool is_allocatable() const {
148 return !is_packed() && _base != NULL;
149 }
150
151 double perc(size_t used, size_t total) const {
152 if (total == 0) {
153 total = 1;
154 }
155 return used / double(total) * 100.0;
156 }
157
158 void print(size_t total_bytes) const {
159 tty->print_cr("%s space: " SIZE_FORMAT_W(9) " [ %4.1f%% of total] out of " SIZE_FORMAT_W(9) " bytes [%5.1f%% used] at " INTPTR_FORMAT,
160 _name, used(), perc(used(), total_bytes), reserved(), perc(used(), reserved()), p2i(_base));
161 }
162 void print_out_of_space_msg(const char* failing_region, size_t needed_bytes) {
163 tty->print("[%-8s] " PTR_FORMAT " - " PTR_FORMAT " capacity =%9d, allocated =%9d",
164 _name, p2i(_base), p2i(_top), int(_end - _base), int(_top - _base));
165 if (strcmp(_name, failing_region) == 0) {
166 tty->print_cr(" required = %d", int(needed_bytes));
167 } else {
168 tty->cr();
169 }
170 }
171
172 void init(const ReservedSpace* rs) {
173 _base = _top = rs->base();
174 _end = rs->end();
175 }
176 void init(char* b, char* t, char* e) {
177 _base = b;
178 _top = t;
179 _end = e;
180 }
181
182 void pack(DumpRegion* next = NULL) {
183 assert(!is_packed(), "sanity");
184 _end = (char*)align_up(_top, Metaspace::reserve_alignment());
185 _is_packed = true;
186 if (next != NULL) {
187 next->_base = next->_top = this->_end;
188 next->_end = MetaspaceShared::shared_rs()->end();
189 }
190 }
191 bool contains(char* p) {
192 return base() <= p && p < top();
193 }
194 };
195
196 DumpRegion _mc_region("mc"), _ro_region("ro"), _rw_region("rw"), _md_region("md"), _od_region("od");
197 DumpRegion _s0_region("s0"), _s1_region("s1");
198
199 char* MetaspaceShared::misc_code_space_alloc(size_t num_bytes) {
200 return _mc_region.allocate(num_bytes);
201 }
202
203 char* MetaspaceShared::read_only_space_alloc(size_t num_bytes) {
204 return _ro_region.allocate(num_bytes);
205 }
206
207 void MetaspaceShared::initialize_shared_rs() {
208 const size_t reserve_alignment = Metaspace::reserve_alignment();
209 bool large_pages = false; // No large pages when dumping the CDS archive.
210 char* shared_base = (char*)align_up((char*)SharedBaseAddress, reserve_alignment);
211
212 #ifdef _LP64
213 const uint64_t UnscaledClassSpaceMax = (uint64_t(max_juint) + 1);
214 const size_t cds_total = align_down(UnscaledClassSpaceMax, reserve_alignment);
215 #else
216 // We don't support archives larger than 256MB on 32-bit due to limited virtual address space.
217 size_t cds_total = align_down(256*M, reserve_alignment);
218 #endif
219
220 // First try to reserve the space at the specified SharedBaseAddress.
221 _shared_rs = ReservedSpace(cds_total, reserve_alignment, large_pages, shared_base);
222 if (_shared_rs.is_reserved()) {
223 assert(shared_base == 0 || _shared_rs.base() == shared_base, "should match");
224 } else {
225 // Get a mmap region anywhere if the SharedBaseAddress fails.
226 _shared_rs = ReservedSpace(cds_total, reserve_alignment, large_pages);
227 }
228 if (!_shared_rs.is_reserved()) {
229 vm_exit_during_initialization("Unable to reserve memory for shared space",
230 err_msg(SIZE_FORMAT " bytes.", cds_total));
231 }
232
233 #ifdef _LP64
234 // During dump time, we allocate 4GB (UnscaledClassSpaceMax) of space and split it up:
235 // + The upper 1 GB is used as the "temporary compressed class space" -- preload_classes()
236 // will store Klasses into this space.
237 // + The lower 3 GB is used for the archive -- when preload_classes() is done,
238 // ArchiveCompactor will copy the class metadata into this space, first the RW parts,
239 // then the RO parts.
240
241 assert(UseCompressedOops && UseCompressedClassPointers,
242 "UseCompressedOops and UseCompressedClassPointers must be set");
243
244 size_t max_archive_size = align_down(cds_total * 3 / 4, reserve_alignment);
245 ReservedSpace tmp_class_space = _shared_rs.last_part(max_archive_size);
246 CompressedClassSpaceSize = align_down(tmp_class_space.size(), reserve_alignment);
247 _shared_rs = _shared_rs.first_part(max_archive_size);
248
249 // Set up compress class pointers.
250 Universe::set_narrow_klass_base((address)_shared_rs.base());
251 if (UseAOT || cds_total > UnscaledClassSpaceMax) {
252 // AOT forces narrow_klass_shift=LogKlassAlignmentInBytes
253 Universe::set_narrow_klass_shift(LogKlassAlignmentInBytes);
254 } else {
255 Universe::set_narrow_klass_shift(0);
256 }
257
258 Metaspace::initialize_class_space(tmp_class_space);
259 tty->print_cr("narrow_klass_base = " PTR_FORMAT ", narrow_klass_shift = %d",
260 p2i(Universe::narrow_klass_base()), Universe::narrow_klass_shift());
261
262 tty->print_cr("Allocated temporary class space: " SIZE_FORMAT " bytes at " PTR_FORMAT,
263 CompressedClassSpaceSize, p2i(tmp_class_space.base()));
264 #endif
265
266 // Start with 0 committed bytes. The memory will be committed as needed by
267 // MetaspaceShared::commit_shared_space_to().
268 if (!_shared_vs.initialize(_shared_rs, 0)) {
269 vm_exit_during_initialization("Unable to allocate memory for shared space");
270 }
271
272 _mc_region.init(&_shared_rs);
273 tty->print_cr("Allocated shared space: " SIZE_FORMAT " bytes at " PTR_FORMAT,
274 _shared_rs.size(), p2i(_shared_rs.base()));
275 }
276
277 void MetaspaceShared::commit_shared_space_to(char* newtop) {
278 assert(DumpSharedSpaces, "dump-time only");
279 char* base = _shared_rs.base();
280 size_t need_committed_size = newtop - base;
281 size_t has_committed_size = _shared_vs.committed_size();
282 if (need_committed_size < has_committed_size) {
283 return;
284 }
285
286 size_t min_bytes = need_committed_size - has_committed_size;
287 size_t preferred_bytes = 1 * M;
288 size_t uncommitted = _shared_vs.reserved_size() - has_committed_size;
289
290 size_t commit = MAX2(min_bytes, preferred_bytes);
291 assert(commit <= uncommitted, "sanity");
292
293 bool result = _shared_vs.expand_by(commit, false);
294 if (!result) {
295 vm_exit_during_initialization(err_msg("Failed to expand shared space to " SIZE_FORMAT " bytes",
296 need_committed_size));
297 }
298
299 log_info(cds)("Expanding shared spaces by " SIZE_FORMAT_W(7) " bytes [total " SIZE_FORMAT_W(9) " bytes ending at %p]",
300 commit, _shared_vs.actual_committed_size(), _shared_vs.high());
301 }
302
303 // Read/write a data stream for restoring/preserving metadata pointers and
304 // miscellaneous data from/to the shared archive file.
305
306 void MetaspaceShared::serialize(SerializeClosure* soc) {
307 int tag = 0;
308 soc->do_tag(--tag);
309
310 // Verify the sizes of various metadata in the system.
311 soc->do_tag(sizeof(Method));
312 soc->do_tag(sizeof(ConstMethod));
313 soc->do_tag(arrayOopDesc::base_offset_in_bytes(T_BYTE));
314 soc->do_tag(sizeof(ConstantPool));
315 soc->do_tag(sizeof(ConstantPoolCache));
316 soc->do_tag(objArrayOopDesc::base_offset_in_bytes());
317 soc->do_tag(typeArrayOopDesc::base_offset_in_bytes(T_BYTE));
318 soc->do_tag(sizeof(Symbol));
319
320 // Dump/restore miscellaneous metadata.
321 Universe::serialize(soc, true);
322 soc->do_tag(--tag);
323
324 // Dump/restore references to commonly used names and signatures.
325 vmSymbols::serialize(soc);
326 soc->do_tag(--tag);
327
328 // Dump/restore the symbol and string tables
329 SymbolTable::serialize(soc);
330 StringTable::serialize(soc);
331 soc->do_tag(--tag);
332
333 soc->do_tag(666);
334 }
335
336 address MetaspaceShared::cds_i2i_entry_code_buffers(size_t total_size) {
337 if (DumpSharedSpaces) {
338 if (_cds_i2i_entry_code_buffers == NULL) {
339 _cds_i2i_entry_code_buffers = (address)misc_code_space_alloc(total_size);
340 _cds_i2i_entry_code_buffers_size = total_size;
341 }
342 } else if (UseSharedSpaces) {
343 assert(_cds_i2i_entry_code_buffers != NULL, "must already been initialized");
344 } else {
345 return NULL;
346 }
347
348 assert(_cds_i2i_entry_code_buffers_size == total_size, "must not change");
349 return _cds_i2i_entry_code_buffers;
350 }
351
352 // CDS code for dumping shared archive.
353
354 // Global object for holding classes that have been loaded. Since this
355 // is run at a safepoint just before exit, this is the entire set of classes.
356 static GrowableArray<Klass*>* _global_klass_objects;
357 class CollectClassesClosure : public KlassClosure {
358 void do_klass(Klass* k) {
359 if (!(k->is_instance_klass() && InstanceKlass::cast(k)->is_in_error_state())) {
360 _global_klass_objects->append_if_missing(k);
361 }
362 }
363 };
364
365 static void remove_unshareable_in_classes() {
366 for (int i = 0; i < _global_klass_objects->length(); i++) {
367 Klass* k = _global_klass_objects->at(i);
368 k->remove_unshareable_info();
369 }
370 }
371
372 static void rewrite_nofast_bytecode(Method* method) {
373 RawBytecodeStream bcs(method);
374 while (!bcs.is_last_bytecode()) {
375 Bytecodes::Code opcode = bcs.raw_next();
376 switch (opcode) {
377 case Bytecodes::_getfield: *bcs.bcp() = Bytecodes::_nofast_getfield; break;
378 case Bytecodes::_putfield: *bcs.bcp() = Bytecodes::_nofast_putfield; break;
379 case Bytecodes::_aload_0: *bcs.bcp() = Bytecodes::_nofast_aload_0; break;
380 case Bytecodes::_iload: {
381 if (!bcs.is_wide()) {
382 *bcs.bcp() = Bytecodes::_nofast_iload;
383 }
384 break;
385 }
386 default: break;
387 }
388 }
389 }
390
391 // Walk all methods in the class list to ensure that they won't be modified at
392 // run time. This includes:
393 // [1] Rewrite all bytecodes as needed, so that the ConstMethod* will not be modified
394 // at run time by RewriteBytecodes/RewriteFrequentPairs
395 // [2] Assign a fingerprint, so one doesn't need to be assigned at run-time.
396 static void rewrite_nofast_bytecodes_and_calculate_fingerprints() {
397 for (int i = 0; i < _global_klass_objects->length(); i++) {
398 Klass* k = _global_klass_objects->at(i);
399 if (k->is_instance_klass()) {
400 InstanceKlass* ik = InstanceKlass::cast(k);
401 for (int i = 0; i < ik->methods()->length(); i++) {
402 Method* m = ik->methods()->at(i);
403 rewrite_nofast_bytecode(m);
404 Fingerprinter fp(m);
405 // The side effect of this call sets method's fingerprint field.
406 fp.fingerprint();
407 }
408 }
409 }
410 }
411
412 static void relocate_cached_class_file() {
413 for (int i = 0; i < _global_klass_objects->length(); i++) {
414 Klass* k = _global_klass_objects->at(i);
415 if (k->is_instance_klass()) {
416 InstanceKlass* ik = InstanceKlass::cast(k);
417 JvmtiCachedClassFileData* p = ik->get_archived_class_data();
418 if (p != NULL) {
419 int size = offset_of(JvmtiCachedClassFileData, data) + p->length;
420 JvmtiCachedClassFileData* q = (JvmtiCachedClassFileData*)_od_region.allocate(size);
421 q->length = p->length;
422 memcpy(q->data, p->data, p->length);
423 ik->set_archived_class_data(q);
424 }
425 }
426 }
427 }
428
429 // Objects of the Metadata types (such as Klass and ConstantPool) have C++ vtables.
430 // (In GCC this is the field <Type>::_vptr, i.e., first word in the object.)
431 //
432 // Addresses of the vtables and the methods may be different across JVM runs,
433 // if libjvm.so is dynamically loaded at a different base address.
434 //
435 // To ensure that the Metadata objects in the CDS archive always have the correct vtable:
436 //
437 // + at dump time: we redirect the _vptr to point to our own vtables inside
438 // the CDS image
439 // + at run time: we clone the actual contents of the vtables from libjvm.so
440 // into our own tables.
441
442 // Currently, the archive contain ONLY the following types of objects that have C++ vtables.
443 #define CPP_VTABLE_PATCH_TYPES_DO(f) \
444 f(ConstantPool) \
445 f(InstanceKlass) \
446 f(InstanceClassLoaderKlass) \
447 f(InstanceMirrorKlass) \
448 f(InstanceRefKlass) \
449 f(Method) \
450 f(ObjArrayKlass) \
451 f(TypeArrayKlass)
452
453 class CppVtableInfo {
454 intptr_t _vtable_size;
455 intptr_t _cloned_vtable[1];
456 public:
457 static int num_slots(int vtable_size) {
458 return 1 + vtable_size; // Need to add the space occupied by _vtable_size;
459 }
460 int vtable_size() { return int(uintx(_vtable_size)); }
461 void set_vtable_size(int n) { _vtable_size = intptr_t(n); }
462 intptr_t* cloned_vtable() { return &_cloned_vtable[0]; }
463 void zero() { memset(_cloned_vtable, 0, sizeof(intptr_t) * vtable_size()); }
464 // Returns the address of the next CppVtableInfo that can be placed immediately after this CppVtableInfo
465 static size_t byte_size(int vtable_size) {
466 CppVtableInfo i;
467 return pointer_delta(&i._cloned_vtable[vtable_size], &i, sizeof(u1));
468 }
469 };
470
471 template <class T> class CppVtableCloner : public T {
472 static intptr_t* vtable_of(Metadata& m) {
473 return *((intptr_t**)&m);
474 }
475 static CppVtableInfo* _info;
476
477 static int get_vtable_length(const char* name);
478
479 public:
480 // Allocate and initialize the C++ vtable, starting from top, but do not go past end.
481 static intptr_t* allocate(const char* name);
482
483 // Clone the vtable to ...
484 static intptr_t* clone_vtable(const char* name, CppVtableInfo* info);
485
486 static void zero_vtable_clone() {
487 assert(DumpSharedSpaces, "dump-time only");
488 _info->zero();
489 }
490
491 // Switch the vtable pointer to point to the cloned vtable.
492 static void patch(Metadata* obj) {
493 assert(DumpSharedSpaces, "dump-time only");
494 *(void**)obj = (void*)(_info->cloned_vtable());
495 }
496
497 static bool is_valid_shared_object(const T* obj) {
498 intptr_t* vptr = *(intptr_t**)obj;
499 return vptr == _info->cloned_vtable();
500 }
501 };
502
503 template <class T> CppVtableInfo* CppVtableCloner<T>::_info = NULL;
504
505 template <class T>
506 intptr_t* CppVtableCloner<T>::allocate(const char* name) {
507 assert(is_aligned(_md_region.top(), sizeof(intptr_t)), "bad alignment");
508 int n = get_vtable_length(name);
509 _info = (CppVtableInfo*)_md_region.allocate(CppVtableInfo::byte_size(n), sizeof(intptr_t));
510 _info->set_vtable_size(n);
511
512 intptr_t* p = clone_vtable(name, _info);
513 assert((char*)p == _md_region.top(), "must be");
514
515 return p;
516 }
517
518 template <class T>
519 intptr_t* CppVtableCloner<T>::clone_vtable(const char* name, CppVtableInfo* info) {
520 if (!DumpSharedSpaces) {
521 assert(_info == 0, "_info is initialized only at dump time");
522 _info = info; // Remember it -- it will be used by MetaspaceShared::is_valid_shared_method()
523 }
524 T tmp; // Allocate temporary dummy metadata object to get to the original vtable.
525 int n = info->vtable_size();
526 intptr_t* srcvtable = vtable_of(tmp);
527 intptr_t* dstvtable = info->cloned_vtable();
528
529 // We already checked (and, if necessary, adjusted n) when the vtables were allocated, so we are
530 // safe to do memcpy.
531 log_debug(cds, vtables)("Copying %3d vtable entries for %s", n, name);
532 memcpy(dstvtable, srcvtable, sizeof(intptr_t) * n);
533 return dstvtable + n;
534 }
535
536 // To determine the size of the vtable for each type, we use the following
537 // trick by declaring 2 subclasses:
538 //
539 // class CppVtableTesterA: public InstanceKlass {virtual int last_virtual_method() {return 1;} };
540 // class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return NULL}; };
541 //
542 // CppVtableTesterA and CppVtableTesterB's vtables have the following properties:
543 // - Their size (N+1) is exactly one more than the size of InstanceKlass's vtable (N)
544 // - The first N entries have are exactly the same as in InstanceKlass's vtable.
545 // - Their last entry is different.
546 //
547 // So to determine the value of N, we just walk CppVtableTesterA and CppVtableTesterB's tables
548 // and find the first entry that's different.
549 //
550 // This works on all C++ compilers supported by Oracle, but you may need to tweak it for more
551 // esoteric compilers.
552
553 template <class T> class CppVtableTesterB: public T {
554 public:
555 virtual int last_virtual_method() {return 1;}
556 };
557
558 template <class T> class CppVtableTesterA : public T {
559 public:
560 virtual void* last_virtual_method() {
561 // Make this different than CppVtableTesterB::last_virtual_method so the C++
562 // compiler/linker won't alias the two functions.
563 return NULL;
564 }
565 };
566
567 template <class T>
568 int CppVtableCloner<T>::get_vtable_length(const char* name) {
569 CppVtableTesterA<T> a;
570 CppVtableTesterB<T> b;
571
572 intptr_t* avtable = vtable_of(a);
573 intptr_t* bvtable = vtable_of(b);
574
575 // Start at slot 1, because slot 0 may be RTTI (on Solaris/Sparc)
576 int vtable_len = 1;
577 for (; ; vtable_len++) {
578 if (avtable[vtable_len] != bvtable[vtable_len]) {
579 break;
580 }
581 }
582 log_debug(cds, vtables)("Found %3d vtable entries for %s", vtable_len, name);
583
584 return vtable_len;
585 }
586
587 #define ALLOC_CPP_VTABLE_CLONE(c) \
588 CppVtableCloner<c>::allocate(#c);
589
590 #define CLONE_CPP_VTABLE(c) \
591 p = CppVtableCloner<c>::clone_vtable(#c, (CppVtableInfo*)p);
592
593 #define ZERO_CPP_VTABLE(c) \
594 CppVtableCloner<c>::zero_vtable_clone();
595
596 // This can be called at both dump time and run time.
597 intptr_t* MetaspaceShared::clone_cpp_vtables(intptr_t* p) {
598 assert(DumpSharedSpaces || UseSharedSpaces, "sanity");
599 CPP_VTABLE_PATCH_TYPES_DO(CLONE_CPP_VTABLE);
600 return p;
601 }
602
603 void MetaspaceShared::zero_cpp_vtable_clones_for_writing() {
604 assert(DumpSharedSpaces, "dump-time only");
605 CPP_VTABLE_PATCH_TYPES_DO(ZERO_CPP_VTABLE);
606 }
607
608 // Allocate and initialize the C++ vtables, starting from top, but do not go past end.
609 void MetaspaceShared::allocate_cpp_vtable_clones() {
610 assert(DumpSharedSpaces, "dump-time only");
611 // Layout (each slot is a intptr_t):
612 // [number of slots in the first vtable = n1]
613 // [ <n1> slots for the first vtable]
614 // [number of slots in the first second = n2]
615 // [ <n2> slots for the second vtable]
616 // ...
617 // The order of the vtables is the same as the CPP_VTAB_PATCH_TYPES_DO macro.
618 CPP_VTABLE_PATCH_TYPES_DO(ALLOC_CPP_VTABLE_CLONE);
619 }
620
621 // Switch the vtable pointer to point to the cloned vtable. We assume the
622 // vtable pointer is in first slot in object.
623 void MetaspaceShared::patch_cpp_vtable_pointers() {
624 int n = _global_klass_objects->length();
625 for (int i = 0; i < n; i++) {
626 Klass* obj = _global_klass_objects->at(i);
627 if (obj->is_instance_klass()) {
628 InstanceKlass* ik = InstanceKlass::cast(obj);
629 if (ik->is_class_loader_instance_klass()) {
630 CppVtableCloner<InstanceClassLoaderKlass>::patch(ik);
631 } else if (ik->is_reference_instance_klass()) {
632 CppVtableCloner<InstanceRefKlass>::patch(ik);
633 } else if (ik->is_mirror_instance_klass()) {
634 CppVtableCloner<InstanceMirrorKlass>::patch(ik);
635 } else {
636 CppVtableCloner<InstanceKlass>::patch(ik);
637 }
638 ConstantPool* cp = ik->constants();
639 CppVtableCloner<ConstantPool>::patch(cp);
640 for (int j = 0; j < ik->methods()->length(); j++) {
641 Method* m = ik->methods()->at(j);
642 CppVtableCloner<Method>::patch(m);
643 assert(CppVtableCloner<Method>::is_valid_shared_object(m), "must be");
644 }
645 } else if (obj->is_objArray_klass()) {
646 CppVtableCloner<ObjArrayKlass>::patch(obj);
647 } else {
648 assert(obj->is_typeArray_klass(), "sanity");
649 CppVtableCloner<TypeArrayKlass>::patch(obj);
650 }
651 }
652 }
653
654 bool MetaspaceShared::is_valid_shared_method(const Method* m) {
655 assert(is_in_shared_space(m), "must be");
656 return CppVtableCloner<Method>::is_valid_shared_object(m);
657 }
658
659 // Closure for serializing initialization data out to a data area to be
660 // written to the shared file.
661
662 class WriteClosure : public SerializeClosure {
663 private:
664 DumpRegion* _dump_region;
665
666 public:
667 WriteClosure(DumpRegion* r) {
668 _dump_region = r;
669 }
670
671 void do_ptr(void** p) {
672 _dump_region->append_intptr_t((intptr_t)*p);
673 }
674
675 void do_u4(u4* p) {
676 void* ptr = (void*)(uintx(*p));
677 do_ptr(&ptr);
678 }
679
680 void do_tag(int tag) {
681 _dump_region->append_intptr_t((intptr_t)tag);
682 }
683
684 void do_region(u_char* start, size_t size) {
685 assert((intptr_t)start % sizeof(intptr_t) == 0, "bad alignment");
686 assert(size % sizeof(intptr_t) == 0, "bad size");
687 do_tag((int)size);
688 while (size > 0) {
689 _dump_region->append_intptr_t(*(intptr_t*)start);
690 start += sizeof(intptr_t);
691 size -= sizeof(intptr_t);
692 }
693 }
694
695 bool reading() const { return false; }
696 };
697
698 // This is for dumping detailed statistics for the allocations
699 // in the shared spaces.
700 class DumpAllocStats : public ResourceObj {
701 public:
702
703 // Here's poor man's enum inheritance
704 #define SHAREDSPACE_OBJ_TYPES_DO(f) \
705 METASPACE_OBJ_TYPES_DO(f) \
706 f(SymbolHashentry) \
707 f(SymbolBucket) \
708 f(StringHashentry) \
709 f(StringBucket) \
710 f(Other)
711
712 enum Type {
713 // Types are MetaspaceObj::ClassType, MetaspaceObj::SymbolType, etc
714 SHAREDSPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_DECLARE)
715 _number_of_types
716 };
717
718 static const char * type_name(Type type) {
719 switch(type) {
720 SHAREDSPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
721 default:
722 ShouldNotReachHere();
723 return NULL;
724 }
725 }
726
727 public:
728 enum { RO = 0, RW = 1 };
729
730 int _counts[2][_number_of_types];
731 int _bytes [2][_number_of_types];
732
733 DumpAllocStats() {
734 memset(_counts, 0, sizeof(_counts));
735 memset(_bytes, 0, sizeof(_bytes));
736 };
737
738 void record(MetaspaceObj::Type type, int byte_size, bool read_only) {
739 assert(int(type) >= 0 && type < MetaspaceObj::_number_of_types, "sanity");
740 int which = (read_only) ? RO : RW;
741 _counts[which][type] ++;
742 _bytes [which][type] += byte_size;
743 }
744
745 void record_other_type(int byte_size, bool read_only) {
746 int which = (read_only) ? RO : RW;
747 _bytes [which][OtherType] += byte_size;
748 }
749 void print_stats(int ro_all, int rw_all, int mc_all, int md_all);
750 };
751
752 void DumpAllocStats::print_stats(int ro_all, int rw_all, int mc_all, int md_all) {
753 // Calculate size of data that was not allocated by Metaspace::allocate()
754 MetaspaceSharedStats *stats = MetaspaceShared::stats();
755
756 // symbols
757 _counts[RO][SymbolHashentryType] = stats->symbol.hashentry_count;
758 _bytes [RO][SymbolHashentryType] = stats->symbol.hashentry_bytes;
759
760 _counts[RO][SymbolBucketType] = stats->symbol.bucket_count;
761 _bytes [RO][SymbolBucketType] = stats->symbol.bucket_bytes;
762
763 // strings
764 _counts[RO][StringHashentryType] = stats->string.hashentry_count;
765 _bytes [RO][StringHashentryType] = stats->string.hashentry_bytes;
766
767 _counts[RO][StringBucketType] = stats->string.bucket_count;
768 _bytes [RO][StringBucketType] = stats->string.bucket_bytes;
769
770 // TODO: count things like dictionary, vtable, etc
771 _bytes[RW][OtherType] += mc_all + md_all;
772 rw_all += mc_all + md_all; // mc/md are mapped Read/Write
773
774 // prevent divide-by-zero
775 if (ro_all < 1) {
776 ro_all = 1;
777 }
778 if (rw_all < 1) {
779 rw_all = 1;
780 }
781
782 int all_ro_count = 0;
783 int all_ro_bytes = 0;
784 int all_rw_count = 0;
785 int all_rw_bytes = 0;
786
787 // To make fmt_stats be a syntactic constant (for format warnings), use #define.
788 #define fmt_stats "%-20s: %8d %10d %5.1f | %8d %10d %5.1f | %8d %10d %5.1f"
789 const char *sep = "--------------------+---------------------------+---------------------------+--------------------------";
790 const char *hdr = " ro_cnt ro_bytes % | rw_cnt rw_bytes % | all_cnt all_bytes %";
791
792 ResourceMark rm;
793 LogMessage(cds) msg;
794 stringStream info_stream;
795
796 info_stream.print_cr("Detailed metadata info (excluding od/st regions; rw stats include md/mc regions):");
797 info_stream.print_cr("%s", hdr);
798 info_stream.print_cr("%s", sep);
799 for (int type = 0; type < int(_number_of_types); type ++) {
800 const char *name = type_name((Type)type);
801 int ro_count = _counts[RO][type];
802 int ro_bytes = _bytes [RO][type];
803 int rw_count = _counts[RW][type];
804 int rw_bytes = _bytes [RW][type];
805 int count = ro_count + rw_count;
806 int bytes = ro_bytes + rw_bytes;
807
808 double ro_perc = 100.0 * double(ro_bytes) / double(ro_all);
809 double rw_perc = 100.0 * double(rw_bytes) / double(rw_all);
810 double perc = 100.0 * double(bytes) / double(ro_all + rw_all);
811
812 info_stream.print_cr(fmt_stats, name,
813 ro_count, ro_bytes, ro_perc,
814 rw_count, rw_bytes, rw_perc,
815 count, bytes, perc);
816
817 all_ro_count += ro_count;
818 all_ro_bytes += ro_bytes;
819 all_rw_count += rw_count;
820 all_rw_bytes += rw_bytes;
821 }
822
823 int all_count = all_ro_count + all_rw_count;
824 int all_bytes = all_ro_bytes + all_rw_bytes;
825
826 double all_ro_perc = 100.0 * double(all_ro_bytes) / double(ro_all);
827 double all_rw_perc = 100.0 * double(all_rw_bytes) / double(rw_all);
828 double all_perc = 100.0 * double(all_bytes) / double(ro_all + rw_all);
829
830 info_stream.print_cr("%s", sep);
831 info_stream.print_cr(fmt_stats, "Total",
832 all_ro_count, all_ro_bytes, all_ro_perc,
833 all_rw_count, all_rw_bytes, all_rw_perc,
834 all_count, all_bytes, all_perc);
835
836 assert(all_ro_bytes == ro_all, "everything should have been counted");
837 assert(all_rw_bytes == rw_all, "everything should have been counted");
838
839 msg.info("%s", info_stream.as_string());
840 #undef fmt_stats
841 }
842
843 // Populate the shared space.
844
845 class VM_PopulateDumpSharedSpace: public VM_Operation {
846 private:
847 GrowableArray<MemRegion> *_string_regions;
848
849 void dump_string_and_symbols();
850 char* dump_read_only_tables();
851 void print_region_stats();
852 public:
853
854 VMOp_Type type() const { return VMOp_PopulateDumpSharedSpace; }
855 void doit(); // outline because gdb sucks
856 static void write_region(FileMapInfo* mapinfo, int region, DumpRegion* space, bool read_only, bool allow_exec);
857 }; // class VM_PopulateDumpSharedSpace
858
859 class SortedSymbolClosure: public SymbolClosure {
860 GrowableArray<Symbol*> _symbols;
861 virtual void do_symbol(Symbol** sym) {
862 assert((*sym)->is_permanent(), "archived symbols must be permanent");
863 _symbols.append(*sym);
864 }
865 static int compare_symbols_by_address(Symbol** a, Symbol** b) {
866 if (a[0] < b[0]) {
867 return -1;
868 } else if (a[0] == b[0]) {
869 return 0;
870 } else {
871 return 1;
872 }
873 }
874
875 public:
876 SortedSymbolClosure() {
877 SymbolTable::symbols_do(this);
878 _symbols.sort(compare_symbols_by_address);
879 }
880 GrowableArray<Symbol*>* get_sorted_symbols() {
881 return &_symbols;
882 }
883 };
884
885 // ArchiveCompactor --
886 //
887 // This class is the central piece of shared archive compaction -- all metaspace data are
888 // initially allocated outside of the shared regions. ArchiveCompactor copies the
889 // metaspace data into their final location in the shared regions.
890
891 class ArchiveCompactor : AllStatic {
892 static DumpAllocStats* _alloc_stats;
893 static SortedSymbolClosure* _ssc;
894
895 static unsigned my_hash(const address& a) {
896 return primitive_hash<address>(a);
897 }
898 static bool my_equals(const address& a0, const address& a1) {
899 return primitive_equals<address>(a0, a1);
900 }
901 typedef ResourceHashtable<
902 address, address,
903 ArchiveCompactor::my_hash, // solaris compiler doesn't like: primitive_hash<address>
904 ArchiveCompactor::my_equals, // solaris compiler doesn't like: primitive_equals<address>
905 16384, ResourceObj::C_HEAP> RelocationTable;
906 static RelocationTable* _new_loc_table;
907
908 public:
909 static void initialize() {
910 _alloc_stats = new(ResourceObj::C_HEAP, mtInternal)DumpAllocStats;
911 _new_loc_table = new(ResourceObj::C_HEAP, mtInternal)RelocationTable;
912 }
913 static DumpAllocStats* alloc_stats() {
914 return _alloc_stats;
915 }
916
917 static void allocate(MetaspaceClosure::Ref* ref, bool read_only) {
918 address obj = ref->obj();
919 int bytes = ref->size() * BytesPerWord;
920 char* p;
921 size_t alignment = BytesPerWord;
922 char* oldtop;
923 char* newtop;
924
925 if (read_only) {
926 oldtop = _ro_region.top();
927 p = _ro_region.allocate(bytes, alignment);
928 newtop = _ro_region.top();
929 } else {
930 oldtop = _rw_region.top();
931 p = _rw_region.allocate(bytes, alignment);
932 newtop = _rw_region.top();
933 }
934 memcpy(p, obj, bytes);
935 bool isnew = _new_loc_table->put(obj, (address)p);
936 assert(isnew, "must be");
937 log_trace(cds)("Copy: " PTR_FORMAT " ==> " PTR_FORMAT " %d", p2i(obj), p2i(p), bytes);
938
939 _alloc_stats->record(ref->msotype(), int(newtop - oldtop), read_only);
940 if (ref->msotype() == MetaspaceObj::SymbolType) {
941 uintx delta = MetaspaceShared::object_delta(p);
942 if (delta > MAX_SHARED_DELTA) {
943 // This is just a sanity check and should not appear in any real world usage. This
944 // happens only if you allocate more than 2GB of Symbols and would require
945 // millions of shared classes.
946 vm_exit_during_initialization("Too many Symbols in the CDS archive",
947 "Please reduce the number of shared classes.");
948 }
949 }
950 }
951
952 static address get_new_loc(MetaspaceClosure::Ref* ref) {
953 address* pp = _new_loc_table->get(ref->obj());
954 assert(pp != NULL, "must be");
955 return *pp;
956 }
957
958 private:
959 // Makes a shallow copy of visited MetaspaceObj's
960 class ShallowCopier: public UniqueMetaspaceClosure {
961 bool _read_only;
962 public:
963 ShallowCopier(bool read_only) : _read_only(read_only) {}
964
965 virtual void do_unique_ref(Ref* ref, bool read_only) {
966 if (read_only == _read_only) {
967 allocate(ref, read_only);
968 }
969 }
970 };
971
972 // Relocate embedded pointers within a MetaspaceObj's shallow copy
973 class ShallowCopyEmbeddedRefRelocator: public UniqueMetaspaceClosure {
974 public:
975 virtual void do_unique_ref(Ref* ref, bool read_only) {
976 address new_loc = get_new_loc(ref);
977 RefRelocator refer;
978 ref->metaspace_pointers_do_at(&refer, new_loc);
979 }
980 };
981
982 // Relocate a reference to point to its shallow copy
983 class RefRelocator: public MetaspaceClosure {
984 public:
985 virtual bool do_ref(Ref* ref, bool read_only) {
986 if (ref->not_null()) {
987 ref->update(get_new_loc(ref));
988 }
989 return false; // Do not recurse.
990 }
991 };
992
993 #ifdef ASSERT
994 class IsRefInArchiveChecker: public MetaspaceClosure {
995 public:
996 virtual bool do_ref(Ref* ref, bool read_only) {
997 if (ref->not_null()) {
998 char* obj = (char*)ref->obj();
999 assert(_ro_region.contains(obj) || _rw_region.contains(obj),
1000 "must be relocated to point to CDS archive");
1001 }
1002 return false; // Do not recurse.
1003 }
1004 };
1005 #endif
1006
1007 public:
1008 static void copy_and_compact() {
1009 // We should no longer allocate anything from the metaspace, so that
1010 // we can have a stable set of MetaspaceObjs to work with.
1011 Metaspace::freeze();
1012
1013 ResourceMark rm;
1014 SortedSymbolClosure the_ssc; // StackObj
1015 _ssc = &the_ssc;
1016
1017 tty->print_cr("Scanning all metaspace objects ... ");
1018 {
1019 // allocate and shallow-copy RW objects, immediately following the MC region
1020 tty->print_cr("Allocating RW objects ... ");
1021 _mc_region.pack(&_rw_region);
1022
1023 ResourceMark rm;
1024 ShallowCopier rw_copier(false);
1025 iterate_roots(&rw_copier);
1026 }
1027 {
1028 // allocate and shallow-copy of RO object, immediately following the RW region
1029 tty->print_cr("Allocating RO objects ... ");
1030 _rw_region.pack(&_ro_region);
1031
1032 ResourceMark rm;
1033 ShallowCopier ro_copier(true);
1034 iterate_roots(&ro_copier);
1035 }
1036 {
1037 tty->print_cr("Relocating embedded pointers ... ");
1038 ResourceMark rm;
1039 ShallowCopyEmbeddedRefRelocator emb_reloc;
1040 iterate_roots(&emb_reloc);
1041 }
1042 {
1043 tty->print_cr("Relocating external roots ... ");
1044 ResourceMark rm;
1045 RefRelocator ext_reloc;
1046 iterate_roots(&ext_reloc);
1047 }
1048
1049 #ifdef ASSERT
1050 {
1051 tty->print_cr("Verifying external roots ... ");
1052 ResourceMark rm;
1053 IsRefInArchiveChecker checker;
1054 iterate_roots(&checker);
1055 }
1056 #endif
1057
1058
1059 // cleanup
1060 _ssc = NULL;
1061 }
1062
1063 // We must relocate the System::_well_known_klasses only after we have copied the
1064 // strings in during dump_string_and_symbols(): during the string copy, we operate on old
1065 // String objects which assert that their klass is the old
1066 // SystemDictionary::String_klass().
1067 static void relocate_well_known_klasses() {
1068 {
1069 tty->print_cr("Relocating SystemDictionary::_well_known_klasses[] ... ");
1070 ResourceMark rm;
1071 RefRelocator ext_reloc;
1072 SystemDictionary::well_known_klasses_do(&ext_reloc);
1073 }
1074 // NOTE: after this point, we shouldn't have any globals that can reach the old
1075 // objects.
1076
1077 // We cannot use any of the objects in the heap anymore (except for the objects
1078 // in the CDS shared string regions) because their headers no longer point to
1079 // valid Klasses.
1080 }
1081
1082 static void iterate_roots(MetaspaceClosure* it) {
1083 GrowableArray<Symbol*>* symbols = _ssc->get_sorted_symbols();
1084 for (int i=0; i<symbols->length(); i++) {
1085 it->push(symbols->adr_at(i));
1086 }
1087 if (_global_klass_objects != NULL) {
1088 // Need to fix up the pointers
1089 for (int i = 0; i < _global_klass_objects->length(); i++) {
1090 // NOTE -- this requires that the vtable is NOT yet patched, or else we are hosed.
1091 it->push(_global_klass_objects->adr_at(i));
1092 }
1093 }
1094 FileMapInfo::metaspace_pointers_do(it);
1095 SystemDictionary::classes_do(it);
1096 Universe::metaspace_pointers_do(it);
1097 SymbolTable::metaspace_pointers_do(it);
1098 vmSymbols::metaspace_pointers_do(it);
1099 }
1100
1101 static Klass* get_relocated_klass(Klass* orig_klass) {
1102 address* pp = _new_loc_table->get((address)orig_klass);
1103 assert(pp != NULL, "must be");
1104 Klass* klass = (Klass*)(*pp);
1105 assert(klass->is_klass(), "must be");
1106 return klass;
1107 }
1108 };
1109
1110 DumpAllocStats* ArchiveCompactor::_alloc_stats;
1111 SortedSymbolClosure* ArchiveCompactor::_ssc;
1112 ArchiveCompactor::RelocationTable* ArchiveCompactor::_new_loc_table;
1113
1114 void VM_PopulateDumpSharedSpace::write_region(FileMapInfo* mapinfo, int region_idx,
1115 DumpRegion* dump_region, bool read_only, bool allow_exec) {
1116 mapinfo->write_region(region_idx, dump_region->base(), dump_region->used(), read_only, allow_exec);
1117 }
1118
1119 void VM_PopulateDumpSharedSpace::dump_string_and_symbols() {
1120 tty->print_cr("Dumping string and symbol tables ...");
1121
1122 NOT_PRODUCT(SymbolTable::verify());
1123 NOT_PRODUCT(StringTable::verify());
1124 SymbolTable::write_to_archive();
1125
1126 // The string space has maximum two regions. See FileMapInfo::write_string_regions() for details.
1127 _string_regions = new GrowableArray<MemRegion>(2);
1128 StringTable::write_to_archive(_string_regions);
1129 }
1130
1131 char* VM_PopulateDumpSharedSpace::dump_read_only_tables() {
1132 char* oldtop = _ro_region.top();
1133 // Reorder the system dictionary. Moving the symbols affects
1134 // how the hash table indices are calculated.
1135 SystemDictionary::reorder_dictionary_for_sharing();
1136 NOT_PRODUCT(SystemDictionary::verify();)
1137
1138 size_t buckets_bytes = SystemDictionary::count_bytes_for_buckets();
1139 char* buckets_top = _ro_region.allocate(buckets_bytes, sizeof(intptr_t));
1140 SystemDictionary::copy_buckets(buckets_top, _ro_region.top());
1141
1142 size_t table_bytes = SystemDictionary::count_bytes_for_table();
1143 char* table_top = _ro_region.allocate(table_bytes, sizeof(intptr_t));
1144 SystemDictionary::copy_table(table_top, _ro_region.top());
1145
1146 // Write the other data to the output array.
1147 WriteClosure wc(&_ro_region);
1148 MetaspaceShared::serialize(&wc);
1149
1150 char* newtop = _ro_region.top();
1151 ArchiveCompactor::alloc_stats()->record_other_type(int(newtop - oldtop), true);
1152 return buckets_top;
1153 }
1154
1155 void VM_PopulateDumpSharedSpace::doit() {
1156 Thread* THREAD = VMThread::vm_thread();
1157
1158 NOT_PRODUCT(SystemDictionary::verify();)
1159 // The following guarantee is meant to ensure that no loader constraints
1160 // exist yet, since the constraints table is not shared. This becomes
1161 // more important now that we don't re-initialize vtables/itables for
1162 // shared classes at runtime, where constraints were previously created.
1163 guarantee(SystemDictionary::constraints()->number_of_entries() == 0,
1164 "loader constraints are not saved");
1165 guarantee(SystemDictionary::placeholders()->number_of_entries() == 0,
1166 "placeholders are not saved");
1167 // Revisit and implement this if we prelink method handle call sites:
1168 guarantee(SystemDictionary::invoke_method_table() == NULL ||
1169 SystemDictionary::invoke_method_table()->number_of_entries() == 0,
1170 "invoke method table is not saved");
1171
1172 // At this point, many classes have been loaded.
1173 // Gather systemDictionary classes in a global array and do everything to
1174 // that so we don't have to walk the SystemDictionary again.
1175 _global_klass_objects = new GrowableArray<Klass*>(1000);
1176 CollectClassesClosure collect_classes;
1177 ClassLoaderDataGraph::loaded_classes_do(&collect_classes);
1178
1179 tty->print_cr("Number of classes %d", _global_klass_objects->length());
1180 {
1181 int num_type_array = 0, num_obj_array = 0, num_inst = 0;
1182 for (int i = 0; i < _global_klass_objects->length(); i++) {
1183 Klass* k = _global_klass_objects->at(i);
1184 if (k->is_instance_klass()) {
1185 num_inst ++;
1186 } else if (k->is_objArray_klass()) {
1187 num_obj_array ++;
1188 } else {
1189 assert(k->is_typeArray_klass(), "sanity");
1190 num_type_array ++;
1191 }
1192 }
1193 tty->print_cr(" instance classes = %5d", num_inst);
1194 tty->print_cr(" obj array classes = %5d", num_obj_array);
1195 tty->print_cr(" type array classes = %5d", num_type_array);
1196 }
1197
1198
1199 // Ensure the ConstMethods won't be modified at run-time
1200 tty->print("Updating ConstMethods ... ");
1201 rewrite_nofast_bytecodes_and_calculate_fingerprints();
1202 tty->print_cr("done. ");
1203
1204 // Remove all references outside the metadata
1205 tty->print("Removing unshareable information ... ");
1206 remove_unshareable_in_classes();
1207 tty->print_cr("done. ");
1208
1209 ArchiveCompactor::initialize();
1210 ArchiveCompactor::copy_and_compact();
1211
1212 dump_string_and_symbols();
1213 ArchiveCompactor::relocate_well_known_klasses();
1214
1215 char* read_only_tables_start = dump_read_only_tables();
1216 _ro_region.pack(&_md_region);
1217
1218 char* vtbl_list = _md_region.top();
1219 MetaspaceShared::allocate_cpp_vtable_clones();
1220 _md_region.pack(&_od_region);
1221
1222 // Relocate the archived class file data into the od region
1223 relocate_cached_class_file();
1224 _od_region.pack();
1225
1226 // The 5 core spaces are allocated consecutively mc->rw->ro->md->od, so there total size
1227 // is just the spaces between the two ends.
1228 size_t core_spaces_size = _od_region.end() - _mc_region.base();
1229 assert(core_spaces_size == (size_t)align_up(core_spaces_size, Metaspace::reserve_alignment()),
1230 "should already be aligned");
1231
1232 // During patching, some virtual methods may be called, so at this point
1233 // the vtables must contain valid methods (as filled in by CppVtableCloner::allocate).
1234 MetaspaceShared::patch_cpp_vtable_pointers();
1235
1236 // The vtable clones contain addresses of the current process.
1237 // We don't want to write these addresses into the archive.
1238 MetaspaceShared::zero_cpp_vtable_clones_for_writing();
1239
1240 // Create and write the archive file that maps the shared spaces.
1241
1242 FileMapInfo* mapinfo = new FileMapInfo();
1243 mapinfo->populate_header(os::vm_allocation_granularity());
1244 mapinfo->set_read_only_tables_start(read_only_tables_start);
1245 mapinfo->set_misc_data_patching_start(vtbl_list);
1246 mapinfo->set_cds_i2i_entry_code_buffers(MetaspaceShared::cds_i2i_entry_code_buffers());
1247 mapinfo->set_cds_i2i_entry_code_buffers_size(MetaspaceShared::cds_i2i_entry_code_buffers_size());
1248 mapinfo->set_core_spaces_size(core_spaces_size);
1249
1250 char* s0_start, *s0_top, *s0_end;
1251 char* s1_start, *s1_top, *s1_end;
1252
1253 for (int pass=1; pass<=2; pass++) {
1254 if (pass == 1) {
1255 // The first pass doesn't actually write the data to disk. All it
1256 // does is to update the fields in the mapinfo->_header.
1257 } else {
1258 // After the first pass, the contents of mapinfo->_header are finalized,
1259 // so we can compute the header's CRC, and write the contents of the header
1260 // and the regions into disk.
1261 mapinfo->open_for_write();
1262 mapinfo->set_header_crc(mapinfo->compute_header_crc());
1263 }
1264 mapinfo->write_header();
1265
1266 // NOTE: md contains the trampoline code for method entries, which are patched at run time,
1267 // so it needs to be read/write.
1268 write_region(mapinfo, MetaspaceShared::mc, &_mc_region, /*read_only=*/false,/*allow_exec=*/true);
1269 write_region(mapinfo, MetaspaceShared::rw, &_rw_region, /*read_only=*/false,/*allow_exec=*/false);
1270 write_region(mapinfo, MetaspaceShared::ro, &_ro_region, /*read_only=*/true, /*allow_exec=*/false);
1271 write_region(mapinfo, MetaspaceShared::md, &_md_region, /*read_only=*/false,/*allow_exec=*/false);
1272 write_region(mapinfo, MetaspaceShared::od, &_od_region, /*read_only=*/true, /*allow_exec=*/false);
1273
1274 mapinfo->write_string_regions(_string_regions,
1275 &s0_start, &s0_top, &s0_end,
1276 &s1_start, &s1_top, &s1_end);
1277 }
1278
1279 mapinfo->close();
1280
1281 // Restore the vtable in case we invoke any virtual methods.
1282 MetaspaceShared::clone_cpp_vtables((intptr_t*)vtbl_list);
1283
1284 _s0_region.init(s0_start, s0_top, s0_end);
1285 _s1_region.init(s1_start, s1_top, s1_end);
1286 print_region_stats();
1287
1288 if (log_is_enabled(Info, cds)) {
1289 ArchiveCompactor::alloc_stats()->print_stats(int(_ro_region.used()), int(_rw_region.used()),
1290 int(_mc_region.used()), int(_md_region.used()));
1291 }
1292 }
1293
1294 void VM_PopulateDumpSharedSpace::print_region_stats() {
1295 // Print statistics of all the regions
1296 const size_t total_reserved = _ro_region.reserved() + _rw_region.reserved() +
1297 _mc_region.reserved() + _md_region.reserved() +
1298 _od_region.reserved() +
1299 _s0_region.reserved() + _s1_region.reserved();
1300 const size_t total_bytes = _ro_region.used() + _rw_region.used() +
1301 _mc_region.used() + _md_region.used() +
1302 _od_region.used() +
1303 _s0_region.used() + _s1_region.used();
1304 const double total_u_perc = total_bytes / double(total_reserved) * 100.0;
1305
1306 _mc_region.print(total_reserved);
1307 _rw_region.print(total_reserved);
1308 _ro_region.print(total_reserved);
1309 _md_region.print(total_reserved);
1310 _od_region.print(total_reserved);
1311 _s0_region.print(total_reserved);
1312 _s1_region.print(total_reserved);
1313
1314 tty->print_cr("total : " SIZE_FORMAT_W(9) " [100.0%% of total] out of " SIZE_FORMAT_W(9) " bytes [%5.1f%% used]",
1315 total_bytes, total_reserved, total_u_perc);
1316 }
1317
1318
1319 // Update a Java object to point its Klass* to the new location after
1320 // shared archive has been compacted.
1321 void MetaspaceShared::relocate_klass_ptr(oop o) {
1322 assert(DumpSharedSpaces, "sanity");
1323 Klass* k = ArchiveCompactor::get_relocated_klass(o->klass());
1324 o->set_klass(k);
1325 }
1326
1327 class LinkSharedClassesClosure : public KlassClosure {
1328 Thread* THREAD;
1329 bool _made_progress;
1330 public:
1331 LinkSharedClassesClosure(Thread* thread) : THREAD(thread), _made_progress(false) {}
1332
1333 void reset() { _made_progress = false; }
1334 bool made_progress() const { return _made_progress; }
1335
1336 void do_klass(Klass* k) {
1337 if (k->is_instance_klass()) {
1338 InstanceKlass* ik = InstanceKlass::cast(k);
1339 // Link the class to cause the bytecodes to be rewritten and the
1340 // cpcache to be created. Class verification is done according
1341 // to -Xverify setting.
1342 _made_progress |= MetaspaceShared::try_link_class(ik, THREAD);
1343 guarantee(!HAS_PENDING_EXCEPTION, "exception in link_class");
1344 }
1345 }
1346 };
1347
1348 class CheckSharedClassesClosure : public KlassClosure {
1349 bool _made_progress;
1350 public:
1351 CheckSharedClassesClosure() : _made_progress(false) {}
1352
1353 void reset() { _made_progress = false; }
1354 bool made_progress() const { return _made_progress; }
1355 void do_klass(Klass* k) {
1356 if (k->is_instance_klass() && InstanceKlass::cast(k)->check_sharing_error_state()) {
1357 _made_progress = true;
1358 }
1359 }
1360 };
1361
1362 void MetaspaceShared::check_shared_class_loader_type(Klass* k) {
1363 if (k->is_instance_klass()) {
1364 InstanceKlass* ik = InstanceKlass::cast(k);
1365 u2 loader_type = ik->loader_type();
1366 ResourceMark rm;
1367 guarantee(loader_type != 0,
1368 "Class loader type is not set for this class %s", ik->name()->as_C_string());
1369 }
1370 }
1371
1372 void MetaspaceShared::link_and_cleanup_shared_classes(TRAPS) {
1373 // We need to iterate because verification may cause additional classes
1374 // to be loaded.
1375 LinkSharedClassesClosure link_closure(THREAD);
1376 do {
1377 link_closure.reset();
1378 ClassLoaderDataGraph::loaded_classes_do(&link_closure);
1379 guarantee(!HAS_PENDING_EXCEPTION, "exception in link_class");
1380 } while (link_closure.made_progress());
1381
1382 if (_has_error_classes) {
1383 // Mark all classes whose super class or interfaces failed verification.
1384 CheckSharedClassesClosure check_closure;
1385 do {
1386 // Not completely sure if we need to do this iteratively. Anyway,
1387 // we should come here only if there are unverifiable classes, which
1388 // shouldn't happen in normal cases. So better safe than sorry.
1389 check_closure.reset();
1390 ClassLoaderDataGraph::loaded_classes_do(&check_closure);
1391 } while (check_closure.made_progress());
1392
1393 if (IgnoreUnverifiableClassesDuringDump) {
1394 // This is useful when running JCK or SQE tests. You should not
1395 // enable this when running real apps.
1396 SystemDictionary::remove_classes_in_error_state();
1397 } else {
1398 tty->print_cr("Please remove the unverifiable classes from your class list and try again");
1399 exit(1);
1400 }
1401 }
1402
1403 // Copy the verification constraints from C_HEAP-alloced GrowableArrays to RO-alloced
1404 // Arrays
1405 SystemDictionaryShared::finalize_verification_constraints();
1406 }
1407
1408 void MetaspaceShared::prepare_for_dumping() {
1409 Arguments::check_unsupported_dumping_properties();
1410 ClassLoader::initialize_shared_path();
1411 FileMapInfo::allocate_classpath_entry_table();
1412 }
1413
1414 // Preload classes from a list, populate the shared spaces and dump to a
1415 // file.
1416 void MetaspaceShared::preload_and_dump(TRAPS) {
1417 { TraceTime timer("Dump Shared Spaces", TRACETIME_LOG(Info, startuptime));
1418 ResourceMark rm;
1419 char class_list_path_str[JVM_MAXPATHLEN];
1420 // Preload classes to be shared.
1421 // Should use some os:: method rather than fopen() here. aB.
1422 const char* class_list_path;
1423 if (SharedClassListFile == NULL) {
1424 // Construct the path to the class list (in jre/lib)
1425 // Walk up two directories from the location of the VM and
1426 // optionally tack on "lib" (depending on platform)
1427 os::jvm_path(class_list_path_str, sizeof(class_list_path_str));
1428 for (int i = 0; i < 3; i++) {
1429 char *end = strrchr(class_list_path_str, *os::file_separator());
1430 if (end != NULL) *end = '\0';
1431 }
1432 int class_list_path_len = (int)strlen(class_list_path_str);
1433 if (class_list_path_len >= 3) {
1434 if (strcmp(class_list_path_str + class_list_path_len - 3, "lib") != 0) {
1435 if (class_list_path_len < JVM_MAXPATHLEN - 4) {
1436 jio_snprintf(class_list_path_str + class_list_path_len,
1437 sizeof(class_list_path_str) - class_list_path_len,
1438 "%slib", os::file_separator());
1439 class_list_path_len += 4;
1440 }
1441 }
1442 }
1443 if (class_list_path_len < JVM_MAXPATHLEN - 10) {
1444 jio_snprintf(class_list_path_str + class_list_path_len,
1445 sizeof(class_list_path_str) - class_list_path_len,
1446 "%sclasslist", os::file_separator());
1447 }
1448 class_list_path = class_list_path_str;
1449 } else {
1450 class_list_path = SharedClassListFile;
1451 }
1452
1453 tty->print_cr("Loading classes to share ...");
1454 _has_error_classes = false;
1455 int class_count = preload_classes(class_list_path, THREAD);
1456 if (ExtraSharedClassListFile) {
1457 class_count += preload_classes(ExtraSharedClassListFile, THREAD);
1458 }
1459 tty->print_cr("Loading classes to share: done.");
1460
1461 log_info(cds)("Shared spaces: preloaded %d classes", class_count);
1462
1463 // Rewrite and link classes
1464 tty->print_cr("Rewriting and linking classes ...");
1465
1466 // Link any classes which got missed. This would happen if we have loaded classes that
1467 // were not explicitly specified in the classlist. E.g., if an interface implemented by class K
1468 // fails verification, all other interfaces that were not specified in the classlist but
1469 // are implemented by K are not verified.
1470 link_and_cleanup_shared_classes(CATCH);
1471 tty->print_cr("Rewriting and linking classes: done");
1472
1473 VM_PopulateDumpSharedSpace op;
1474 VMThread::execute(&op);
1475 }
1476
1477 if (PrintSystemDictionaryAtExit) {
1478 SystemDictionary::print();
1479 }
1480
1481 // Since various initialization steps have been undone by this process,
1482 // it is not reasonable to continue running a java process.
1483 exit(0);
1484 }
1485
1486
1487 int MetaspaceShared::preload_classes(const char* class_list_path, TRAPS) {
1488 ClassListParser parser(class_list_path);
1489 int class_count = 0;
1490
1491 while (parser.parse_one_line()) {
1492 Klass* klass = ClassLoaderExt::load_one_class(&parser, THREAD);
1493
1494 CLEAR_PENDING_EXCEPTION;
1495 if (klass != NULL) {
1496 if (log_is_enabled(Trace, cds)) {
1497 ResourceMark rm;
1498 log_trace(cds)("Shared spaces preloaded: %s", klass->external_name());
1499 }
1500
1501 InstanceKlass* ik = InstanceKlass::cast(klass);
1502
1503 // Link the class to cause the bytecodes to be rewritten and the
1504 // cpcache to be created. The linking is done as soon as classes
1505 // are loaded in order that the related data structures (klass and
1506 // cpCache) are located together.
1507 try_link_class(ik, THREAD);
1508 guarantee(!HAS_PENDING_EXCEPTION, "exception in link_class");
1509
1510 class_count++;
1511 }
1512 }
1513
1514 return class_count;
1515 }
1516
1517 // Returns true if the class's status has changed
1518 bool MetaspaceShared::try_link_class(InstanceKlass* ik, TRAPS) {
1519 assert(DumpSharedSpaces, "should only be called during dumping");
1520 if (ik->init_state() < InstanceKlass::linked) {
1521 bool saved = BytecodeVerificationLocal;
1522 if (!(ik->is_shared_boot_class())) {
1523 // The verification decision is based on BytecodeVerificationRemote
1524 // for non-system classes. Since we are using the NULL classloader
1525 // to load non-system classes during dumping, we need to temporarily
1526 // change BytecodeVerificationLocal to be the same as
1527 // BytecodeVerificationRemote. Note this can cause the parent system
1528 // classes also being verified. The extra overhead is acceptable during
1529 // dumping.
1530 BytecodeVerificationLocal = BytecodeVerificationRemote;
1531 }
1532 ik->link_class(THREAD);
1533 if (HAS_PENDING_EXCEPTION) {
1534 ResourceMark rm;
1535 tty->print_cr("Preload Warning: Verification failed for %s",
1536 ik->external_name());
1537 CLEAR_PENDING_EXCEPTION;
1538 ik->set_in_error_state();
1539 _has_error_classes = true;
1540 }
1541 BytecodeVerificationLocal = saved;
1542 return true;
1543 } else {
1544 return false;
1545 }
1546 }
1547
1548 // Closure for serializing initialization data in from a data area
1549 // (ptr_array) read from the shared file.
1550
1551 class ReadClosure : public SerializeClosure {
1552 private:
1553 intptr_t** _ptr_array;
1554
1555 inline intptr_t nextPtr() {
1556 return *(*_ptr_array)++;
1557 }
1558
1559 public:
1560 ReadClosure(intptr_t** ptr_array) { _ptr_array = ptr_array; }
1561
1562 void do_ptr(void** p) {
1563 assert(*p == NULL, "initializing previous initialized pointer.");
1564 intptr_t obj = nextPtr();
1565 assert((intptr_t)obj >= 0 || (intptr_t)obj < -100,
1566 "hit tag while initializing ptrs.");
1567 *p = (void*)obj;
1568 }
1569
1570 void do_u4(u4* p) {
1571 intptr_t obj = nextPtr();
1572 *p = (u4)(uintx(obj));
1573 }
1574
1575 void do_tag(int tag) {
1576 int old_tag;
1577 old_tag = (int)(intptr_t)nextPtr();
1578 // do_int(&old_tag);
1579 assert(tag == old_tag, "old tag doesn't match");
1580 FileMapInfo::assert_mark(tag == old_tag);
1581 }
1582
1583 void do_region(u_char* start, size_t size) {
1584 assert((intptr_t)start % sizeof(intptr_t) == 0, "bad alignment");
1585 assert(size % sizeof(intptr_t) == 0, "bad size");
1586 do_tag((int)size);
1587 while (size > 0) {
1588 *(intptr_t*)start = nextPtr();
1589 start += sizeof(intptr_t);
1590 size -= sizeof(intptr_t);
1591 }
1592 }
1593
1594 bool reading() const { return true; }
1595 };
1596
1597 // Return true if given address is in the mapped shared space.
1598 bool MetaspaceShared::is_in_shared_space(const void* p) {
1599 return UseSharedSpaces && FileMapInfo::current_info()->is_in_shared_space(p);
1600 }
1601
1602 // Return true if given address is in the misc data region
1603 bool MetaspaceShared::is_in_shared_region(const void* p, int idx) {
1604 return UseSharedSpaces && FileMapInfo::current_info()->is_in_shared_region(p, idx);
1605 }
1606
1607 bool MetaspaceShared::is_in_trampoline_frame(address addr) {
1608 if (UseSharedSpaces && is_in_shared_region(addr, MetaspaceShared::mc)) {
1609 return true;
1610 }
1611 return false;
1612 }
1613
1614 void MetaspaceShared::print_shared_spaces() {
1615 if (UseSharedSpaces) {
1616 FileMapInfo::current_info()->print_shared_spaces();
1617 }
1618 }
1619
1620
1621 // Map shared spaces at requested addresses and return if succeeded.
1622 bool MetaspaceShared::map_shared_spaces(FileMapInfo* mapinfo) {
1623 size_t image_alignment = mapinfo->alignment();
1624
1625 #ifndef _WINDOWS
1626 // Map in the shared memory and then map the regions on top of it.
1627 // On Windows, don't map the memory here because it will cause the
1628 // mappings of the regions to fail.
1629 ReservedSpace shared_rs = mapinfo->reserve_shared_memory();
1630 if (!shared_rs.is_reserved()) return false;
1631 #endif
1632
1633 assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
1634
1635 char* _ro_base = NULL;
1636 char* _rw_base = NULL;
1637 char* _mc_base = NULL;
1638 char* _md_base = NULL;
1639 char* _od_base = NULL;
1640
1641 // Map each shared region
1642 if ((_mc_base = mapinfo->map_region(mc)) != NULL &&
1643 mapinfo->verify_region_checksum(mc) &&
1644 (_rw_base = mapinfo->map_region(rw)) != NULL &&
1645 mapinfo->verify_region_checksum(rw) &&
1646 (_ro_base = mapinfo->map_region(ro)) != NULL &&
1647 mapinfo->verify_region_checksum(ro) &&
1648 (_md_base = mapinfo->map_region(md)) != NULL &&
1649 mapinfo->verify_region_checksum(md) &&
1650 (_od_base = mapinfo->map_region(od)) != NULL &&
1651 mapinfo->verify_region_checksum(od) &&
1652 (image_alignment == (size_t)os::vm_allocation_granularity()) &&
1653 mapinfo->validate_classpath_entry_table()) {
1654 // Success (no need to do anything)
1655 return true;
1656 } else {
1657 // If there was a failure in mapping any of the spaces, unmap the ones
1658 // that succeeded
1659 if (_ro_base != NULL) mapinfo->unmap_region(ro);
1660 if (_rw_base != NULL) mapinfo->unmap_region(rw);
1661 if (_mc_base != NULL) mapinfo->unmap_region(mc);
1662 if (_md_base != NULL) mapinfo->unmap_region(md);
1663 if (_od_base != NULL) mapinfo->unmap_region(od);
1664 #ifndef _WINDOWS
1665 // Release the entire mapped region
1666 shared_rs.release();
1667 #endif
1668 // If -Xshare:on is specified, print out the error message and exit VM,
1669 // otherwise, set UseSharedSpaces to false and continue.
1670 if (RequireSharedSpaces || PrintSharedArchiveAndExit) {
1671 vm_exit_during_initialization("Unable to use shared archive.", "Failed map_region for using -Xshare:on.");
1672 } else {
1673 FLAG_SET_DEFAULT(UseSharedSpaces, false);
1674 }
1675 return false;
1676 }
1677 }
1678
1679 // Read the miscellaneous data from the shared file, and
1680 // serialize it out to its various destinations.
1681
1682 void MetaspaceShared::initialize_shared_spaces() {
1683 FileMapInfo *mapinfo = FileMapInfo::current_info();
1684 _cds_i2i_entry_code_buffers = mapinfo->cds_i2i_entry_code_buffers();
1685 _cds_i2i_entry_code_buffers_size = mapinfo->cds_i2i_entry_code_buffers_size();
1686 _core_spaces_size = mapinfo->core_spaces_size();
1687 char* buffer = mapinfo->misc_data_patching_start();
1688 clone_cpp_vtables((intptr_t*)buffer);
1689
1690 // The rest of the data is now stored in the RW region
1691 buffer = mapinfo->read_only_tables_start();
1692 int sharedDictionaryLen = *(intptr_t*)buffer;
1693 buffer += sizeof(intptr_t);
1694 int number_of_entries = *(intptr_t*)buffer;
1695 buffer += sizeof(intptr_t);
1696 SystemDictionary::set_shared_dictionary((HashtableBucket<mtClass>*)buffer,
1697 sharedDictionaryLen,
1698 number_of_entries);
1699 buffer += sharedDictionaryLen;
1700
1701 // The following data are the linked list elements
1702 // (HashtableEntry objects) for the shared dictionary table.
1703
1704 int len = *(intptr_t*)buffer; // skip over shared dictionary entries
1705 buffer += sizeof(intptr_t);
1706 buffer += len;
1707
1708 // Verify various attributes of the archive, plus initialize the
1709 // shared string/symbol tables
1710 intptr_t* array = (intptr_t*)buffer;
1711 ReadClosure rc(&array);
1712 serialize(&rc);
1713
1714 // Initialize the run-time symbol table.
1715 SymbolTable::create_table();
1716
1717 // Close the mapinfo file
1718 mapinfo->close();
1719
1720 if (PrintSharedArchiveAndExit) {
1721 if (PrintSharedDictionary) {
1722 tty->print_cr("\nShared classes:\n");
1723 SystemDictionary::print_shared(false);
1724 }
1725 if (_archive_loading_failed) {
1726 tty->print_cr("archive is invalid");
1727 vm_exit(1);
1728 } else {
1729 tty->print_cr("archive is valid");
1730 vm_exit(0);
1731 }
1732 }
1733 }
1734
1735 void MetaspaceShared::fixup_shared_string_regions() {
1736 FileMapInfo *mapinfo = FileMapInfo::current_info();
1737 mapinfo->fixup_string_regions();
1738 }
1739
1740 // JVM/TI RedefineClasses() support:
1741 bool MetaspaceShared::remap_shared_readonly_as_readwrite() {
1742 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1743
1744 if (UseSharedSpaces) {
1745 // remap the shared readonly space to shared readwrite, private
1746 FileMapInfo* mapinfo = FileMapInfo::current_info();
1747 if (!mapinfo->remap_shared_readonly_as_readwrite()) {
1748 return false;
1749 }
1750 _remapped_readwrite = true;
1751 }
1752 return true;
1753 }
1754
1755 void MetaspaceShared::report_out_of_space(const char* name, size_t needed_bytes) {
1756 // This is highly unlikely to happen on 64-bits because we have reserved a 4GB space.
1757 // On 32-bit we reserve only 256MB so you could run out of space with 100,000 classes
1758 // or so.
1759 _mc_region.print_out_of_space_msg(name, needed_bytes);
1760 _rw_region.print_out_of_space_msg(name, needed_bytes);
1761 _ro_region.print_out_of_space_msg(name, needed_bytes);
1762 _md_region.print_out_of_space_msg(name, needed_bytes);
1763 _od_region.print_out_of_space_msg(name, needed_bytes);
1764
1765 vm_exit_during_initialization(err_msg("Unable to allocate from '%s' region", name),
1766 "Please reduce the number of shared classes.");
1767 }