1 /*
2 * Copyright (c) 2011, 2013, 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.
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23 */
24 #ifndef SHARE_VM_MEMORY_METASPACE_HPP
25 #define SHARE_VM_MEMORY_METASPACE_HPP
26
27 #include "memory/allocation.hpp"
28 #include "memory/memRegion.hpp"
29 #include "runtime/virtualspace.hpp"
30 #include "utilities/exceptions.hpp"
31
32 // Metaspace
33 //
34 // Metaspaces are Arenas for the VM's metadata.
35 // They are allocated one per class loader object, and one for the null
36 // bootstrap class loader
37 // Eventually for bootstrap loader we'll have a read-only section and read-write
38 // to write for DumpSharedSpaces and read for UseSharedSpaces
39 //
40 // block X ---+ +-------------------+
41 // | | Virtualspace |
42 // | | |
43 // | | |
44 // | |-------------------|
45 // | || Chunk |
46 // | || |
47 // | ||---------- |
48 // +------>||| block 0 | |
49 // ||---------- |
50 // ||| block 1 | |
51 // ||---------- |
52 // || |
53 // |-------------------|
54 // | |
55 // | |
56 // +-------------------+
57 //
58
59 class ClassLoaderData;
60 class Metablock;
61 class MetaWord;
62 class Mutex;
63 class outputStream;
64 class SpaceManager;
65
66 // Metaspaces each have a SpaceManager and allocations
67 // are done by the SpaceManager. Allocations are done
68 // out of the current Metachunk. When the current Metachunk
69 // is exhausted, the SpaceManager gets a new one from
70 // the current VirtualSpace. When the VirtualSpace is exhausted
71 // the SpaceManager gets a new one. The SpaceManager
72 // also manages freelists of available Chunks.
73 //
74 // Currently the space manager maintains the list of
75 // virtual spaces and the list of chunks in use. Its
76 // allocate() method returns a block for use as a
77 // quantum of metadata.
78
79 class VirtualSpaceList;
80
81 class Metaspace : public CHeapObj<mtClass> {
82 friend class VMStructs;
83 friend class SpaceManager;
84 friend class VM_CollectForMetadataAllocation;
85 friend class MetaspaceGC;
86 friend class MetaspaceAux;
87
88 public:
89 enum MetadataType {ClassType = 0,
90 NonClassType = ClassType + 1,
91 MetadataTypeCount = ClassType + 2
92 };
93 enum MetaspaceType {
94 StandardMetaspaceType,
95 BootMetaspaceType,
96 ROMetaspaceType,
97 ReadWriteMetaspaceType,
98 AnonymousMetaspaceType,
99 ReflectionMetaspaceType
100 };
101
102 private:
103 void initialize(Mutex* lock, MetaspaceType type);
104
105 // Align up the word size to the allocation word size
106 static size_t align_word_size_up(size_t);
107
108 static size_t _first_chunk_word_size;
109 static size_t _first_class_chunk_word_size;
110
111 SpaceManager* _vsm;
112 SpaceManager* vsm() const { return _vsm; }
113
114 SpaceManager* _class_vsm;
115 SpaceManager* class_vsm() const { return _class_vsm; }
116
117 // Allocate space for metadata of type mdtype. This is space
118 // within a Metachunk and is used by
119 // allocate(ClassLoaderData*, size_t, bool, MetadataType, TRAPS)
120 // which returns a Metablock.
121 MetaWord* allocate(size_t word_size, MetadataType mdtype);
122
123 // Virtual Space lists for both classes and other metadata
124 static VirtualSpaceList* _space_list;
125 static VirtualSpaceList* _class_space_list;
126
127 static VirtualSpaceList* space_list() { return _space_list; }
128 static VirtualSpaceList* class_space_list() { return _class_space_list; }
129
130 // This is used by DumpSharedSpaces only, where only _vsm is used. So we will
131 // maintain a single list for now.
132 void record_allocation(void* ptr, MetaspaceObj::Type type, size_t word_size);
133
134 class AllocRecord : public CHeapObj<mtClass> {
135 public:
136 AllocRecord(address ptr, MetaspaceObj::Type type, int byte_size)
137 : _next(NULL), _ptr(ptr), _type(type), _byte_size(byte_size) {}
138 AllocRecord *_next;
139 address _ptr;
140 MetaspaceObj::Type _type;
141 int _byte_size;
142 };
143
144 AllocRecord * _alloc_record_head;
145 AllocRecord * _alloc_record_tail;
146
147 public:
148
149 Metaspace(Mutex* lock, MetaspaceType type);
150 ~Metaspace();
151
152 // Initialize globals for Metaspace
153 static void global_initialize();
154 static void initialize_class_space(ReservedSpace rs);
155
156 static size_t first_chunk_word_size() { return _first_chunk_word_size; }
157 static size_t first_class_chunk_word_size() { return _first_class_chunk_word_size; }
158
159 char* bottom() const;
160 size_t used_words_slow(MetadataType mdtype) const;
161 size_t free_words(MetadataType mdtype) const;
162 size_t capacity_words_slow(MetadataType mdtype) const;
163 size_t waste_words(MetadataType mdtype) const;
164
165 size_t used_bytes_slow(MetadataType mdtype) const;
166 size_t capacity_bytes_slow(MetadataType mdtype) const;
167
168 static Metablock* allocate(ClassLoaderData* loader_data, size_t word_size,
169 bool read_only, MetaspaceObj::Type type, TRAPS);
170 void deallocate(MetaWord* ptr, size_t byte_size, bool is_class);
171
172 MetaWord* expand_and_allocate(size_t size,
173 MetadataType mdtype);
174
175 static bool is_initialized() { return _class_space_list != NULL; }
176
177 static bool contains(const void *ptr);
178 void dump(outputStream* const out) const;
179
180 // Free empty virtualspaces
181 static void purge();
182
183 void print_on(outputStream* st) const;
184 // Debugging support
185 void verify();
186
187 class AllocRecordClosure : public StackObj {
188 public:
189 virtual void doit(address ptr, MetaspaceObj::Type type, int byte_size) = 0;
190 };
191
192 void iterate(AllocRecordClosure *closure);
193 };
194
195 class MetaspaceAux : AllStatic {
196
197 // Statistics for class space and data space in metaspace.
198
199 // These methods iterate over the classloader data graph
200 // for the given Metaspace type. These are slow.
201 static size_t used_bytes_slow(Metaspace::MetadataType mdtype);
202 static size_t free_in_bytes(Metaspace::MetadataType mdtype);
203 static size_t capacity_bytes_slow(Metaspace::MetadataType mdtype);
204
205 // Iterates over the virtual space list.
206 static size_t reserved_in_bytes(Metaspace::MetadataType mdtype);
207
208 static size_t free_chunks_total(Metaspace::MetadataType mdtype);
209 static size_t free_chunks_total_in_bytes(Metaspace::MetadataType mdtype);
210
211 public:
212 // Running sum of space in all Metachunks that has been
213 // allocated to a Metaspace. This is used instead of
214 // iterating over all the classloaders. One for each
215 // type of Metadata
216 static size_t _allocated_capacity_words[Metaspace:: MetadataTypeCount];
217 // Running sum of space in all Metachunks that have
218 // are being used for metadata. One for each
219 // type of Metadata.
220 static size_t _allocated_used_words[Metaspace:: MetadataTypeCount];
221
222 public:
223 // Decrement and increment _allocated_capacity_words
224 static void dec_capacity(Metaspace::MetadataType type, size_t words);
225 static void inc_capacity(Metaspace::MetadataType type, size_t words);
226
227 // Decrement and increment _allocated_used_words
228 static void dec_used(Metaspace::MetadataType type, size_t words);
229 static void inc_used(Metaspace::MetadataType type, size_t words);
230
231 // Total of space allocated to metadata in all Metaspaces.
232 // This sums the space used in each Metachunk by
233 // iterating over the classloader data graph
234 static size_t used_bytes_slow() {
235 return used_bytes_slow(Metaspace::ClassType) +
236 used_bytes_slow(Metaspace::NonClassType);
237 }
238
239 // Used by MetaspaceCounters
240 static size_t free_chunks_total();
241 static size_t free_chunks_total_in_bytes();
242
243 static size_t allocated_capacity_words(Metaspace::MetadataType mdtype) {
244 return _allocated_capacity_words[mdtype];
245 }
246 static size_t allocated_capacity_words() {
247 return _allocated_capacity_words[Metaspace::ClassType] +
248 _allocated_capacity_words[Metaspace::NonClassType];
249 }
250 static size_t allocated_capacity_bytes(Metaspace::MetadataType mdtype) {
251 return allocated_capacity_words(mdtype) * BytesPerWord;
252 }
253 static size_t allocated_capacity_bytes() {
254 return allocated_capacity_words() * BytesPerWord;
255 }
256
257 static size_t allocated_used_words(Metaspace::MetadataType mdtype) {
258 return _allocated_used_words[mdtype];
259 }
260 static size_t allocated_used_words() {
261 return _allocated_used_words[Metaspace::ClassType] +
262 _allocated_used_words[Metaspace::NonClassType];
263 }
264 static size_t allocated_used_bytes(Metaspace::MetadataType mdtype) {
265 return allocated_used_words(mdtype) * BytesPerWord;
266 }
267 static size_t allocated_used_bytes() {
268 return allocated_used_words() * BytesPerWord;
269 }
270
271 static size_t free_bytes();
272
273 // Total capacity in all Metaspaces
274 static size_t capacity_bytes_slow() {
275 #ifdef PRODUCT
276 // Use allocated_capacity_bytes() in PRODUCT instead of this function.
277 guarantee(false, "Should not call capacity_bytes_slow() in the PRODUCT");
278 #endif
279 size_t class_capacity = capacity_bytes_slow(Metaspace::ClassType);
280 size_t non_class_capacity = capacity_bytes_slow(Metaspace::NonClassType);
281 assert(allocated_capacity_bytes() == class_capacity + non_class_capacity,
282 err_msg("bad accounting: allocated_capacity_bytes() " SIZE_FORMAT
283 " class_capacity + non_class_capacity " SIZE_FORMAT
284 " class_capacity " SIZE_FORMAT " non_class_capacity " SIZE_FORMAT,
285 allocated_capacity_bytes(), class_capacity + non_class_capacity,
286 class_capacity, non_class_capacity));
287
288 return class_capacity + non_class_capacity;
289 }
290
291 // Total space reserved in all Metaspaces
292 static size_t reserved_in_bytes() {
293 return reserved_in_bytes(Metaspace::ClassType) +
294 reserved_in_bytes(Metaspace::NonClassType);
295 }
296
297 static size_t min_chunk_size();
298
299 // Print change in used metadata.
300 static void print_metaspace_change(size_t prev_metadata_used);
301 static void print_on(outputStream * out);
302 static void print_on(outputStream * out, Metaspace::MetadataType mdtype);
303
304 static void print_waste(outputStream* out);
305 static void dump(outputStream* out);
306 static void verify_free_chunks();
307 // Checks that the values returned by allocated_capacity_bytes() and
308 // capacity_bytes_slow() are the same.
309 static void verify_capacity();
310 static void verify_used();
311 static void verify_metrics();
312 };
313
314 // Metaspace are deallocated when their class loader are GC'ed.
315 // This class implements a policy for inducing GC's to recover
316 // Metaspaces.
317
318 class MetaspaceGC : AllStatic {
319
320 // The current high-water-mark for inducing a GC. When
321 // the capacity of all space in the virtual lists reaches this value,
322 // a GC is induced and the value is increased. This should be changed
323 // to the space actually used for allocations to avoid affects of
324 // fragmentation losses to partially used chunks. Size is in words.
325 static size_t _capacity_until_GC;
326
327 // After a GC is done any allocation that fails should try to expand
328 // the capacity of the Metaspaces. This flag is set during attempts
329 // to allocate in the VMGCOperation that does the GC.
330 static bool _expand_after_GC;
331
332 // For a CMS collection, signal that a concurrent collection should
333 // be started.
334 static bool _should_concurrent_collect;
335
336 static uint _shrink_factor;
337
338 static void set_capacity_until_GC(size_t v) { _capacity_until_GC = v; }
339
340 static size_t shrink_factor() { return _shrink_factor; }
341 void set_shrink_factor(uint v) { _shrink_factor = v; }
342
343 public:
344
345 static size_t capacity_until_GC() { return _capacity_until_GC; }
346 static void inc_capacity_until_GC(size_t v) { _capacity_until_GC += v; }
347 static void dec_capacity_until_GC(size_t v) {
348 _capacity_until_GC = _capacity_until_GC > v ? _capacity_until_GC - v : 0;
349 }
350 static bool expand_after_GC() { return _expand_after_GC; }
351 static void set_expand_after_GC(bool v) { _expand_after_GC = v; }
352
353 static bool should_concurrent_collect() { return _should_concurrent_collect; }
354 static void set_should_concurrent_collect(bool v) {
355 _should_concurrent_collect = v;
356 }
357
358 // The amount to increase the high-water-mark (_capacity_until_GC)
359 static size_t delta_capacity_until_GC(size_t word_size);
360
361 // It is expected that this will be called when the current capacity
362 // has been used and a GC should be considered.
363 static bool should_expand(VirtualSpaceList* vsl, size_t word_size);
364
365 // Calculate the new high-water mark at which to induce
366 // a GC.
367 static void compute_new_size();
368 };
369
370 #endif // SHARE_VM_MEMORY_METASPACE_HPP