Fri, 20 Sep 2013 10:53:28 +0200
8024974: Incorrect use of GC_locker::is_active()
Summary: SymbolTable and StringTable can make calls to GC_locker::is_active() outside a safepoint. This isn't safe because the GC_locker active state (lock count) is only updated at a safepoint and only remains valid as long as _needs_gc is true. However, outside a safepoint_needs_gc can change to false at any time, which makes it impossible to do a correct call to is_active() in that context. In this case these calls can just be removed since the input argument to basic_add() should never be on the heap and so there's no need to check the GC_locker state. This change also adjusts the assert() in is_active() to makes sure all calls to this function are always done under a safepoint.
Reviewed-by: brutisso, dcubed
Contributed-by: per.liden@oracle.com
1 /*
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25 #ifndef SHARE_VM_MEMORY_COLLECTORPOLICY_HPP
26 #define SHARE_VM_MEMORY_COLLECTORPOLICY_HPP
28 #include "memory/allocation.hpp"
29 #include "memory/barrierSet.hpp"
30 #include "memory/generationSpec.hpp"
31 #include "memory/genRemSet.hpp"
32 #include "utilities/macros.hpp"
34 // This class (or more correctly, subtypes of this class)
35 // are used to define global garbage collector attributes.
36 // This includes initialization of generations and any other
37 // shared resources they may need.
38 //
39 // In general, all flag adjustment and validation should be
40 // done in initialize_flags(), which is called prior to
41 // initialize_size_info().
42 //
43 // This class is not fully developed yet. As more collector(s)
44 // are added, it is expected that we will come across further
45 // behavior that requires global attention. The correct place
46 // to deal with those issues is this class.
48 // Forward declarations.
49 class GenCollectorPolicy;
50 class TwoGenerationCollectorPolicy;
51 class AdaptiveSizePolicy;
52 #if INCLUDE_ALL_GCS
53 class ConcurrentMarkSweepPolicy;
54 class G1CollectorPolicy;
55 #endif // INCLUDE_ALL_GCS
57 class GCPolicyCounters;
58 class MarkSweepPolicy;
60 class CollectorPolicy : public CHeapObj<mtGC> {
61 protected:
62 GCPolicyCounters* _gc_policy_counters;
64 // Requires that the concrete subclass sets the alignment constraints
65 // before calling.
66 virtual void initialize_flags();
67 virtual void initialize_size_info();
69 size_t _initial_heap_byte_size;
70 size_t _max_heap_byte_size;
71 size_t _min_heap_byte_size;
73 size_t _min_alignment;
74 size_t _max_alignment;
76 // The sizing of the heap are controlled by a sizing policy.
77 AdaptiveSizePolicy* _size_policy;
79 // Set to true when policy wants soft refs cleared.
80 // Reset to false by gc after it clears all soft refs.
81 bool _should_clear_all_soft_refs;
82 // Set to true by the GC if the just-completed gc cleared all
83 // softrefs. This is set to true whenever a gc clears all softrefs, and
84 // set to false each time gc returns to the mutator. For example, in the
85 // ParallelScavengeHeap case the latter would be done toward the end of
86 // mem_allocate() where it returns op.result()
87 bool _all_soft_refs_clear;
89 CollectorPolicy() :
90 _min_alignment(1),
91 _max_alignment(1),
92 _initial_heap_byte_size(0),
93 _max_heap_byte_size(0),
94 _min_heap_byte_size(0),
95 _size_policy(NULL),
96 _should_clear_all_soft_refs(false),
97 _all_soft_refs_clear(false)
98 {}
100 public:
101 // Return maximum heap alignment that may be imposed by the policy
102 static size_t compute_max_alignment();
104 void set_min_alignment(size_t align) { _min_alignment = align; }
105 size_t min_alignment() { return _min_alignment; }
106 void set_max_alignment(size_t align) { _max_alignment = align; }
107 size_t max_alignment() { return _max_alignment; }
109 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
110 void set_initial_heap_byte_size(size_t v) { _initial_heap_byte_size = v; }
111 size_t max_heap_byte_size() { return _max_heap_byte_size; }
112 void set_max_heap_byte_size(size_t v) { _max_heap_byte_size = v; }
113 size_t min_heap_byte_size() { return _min_heap_byte_size; }
114 void set_min_heap_byte_size(size_t v) { _min_heap_byte_size = v; }
116 enum Name {
117 CollectorPolicyKind,
118 TwoGenerationCollectorPolicyKind,
119 ConcurrentMarkSweepPolicyKind,
120 ASConcurrentMarkSweepPolicyKind,
121 G1CollectorPolicyKind
122 };
124 AdaptiveSizePolicy* size_policy() { return _size_policy; }
125 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
126 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
127 // Returns the current value of _should_clear_all_soft_refs.
128 // _should_clear_all_soft_refs is set to false as a side effect.
129 bool use_should_clear_all_soft_refs(bool v);
130 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
131 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
133 // Called by the GC after Soft Refs have been cleared to indicate
134 // that the request in _should_clear_all_soft_refs has been fulfilled.
135 void cleared_all_soft_refs();
137 // Identification methods.
138 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
139 virtual TwoGenerationCollectorPolicy* as_two_generation_policy() { return NULL; }
140 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
141 #if INCLUDE_ALL_GCS
142 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
143 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
144 #endif // INCLUDE_ALL_GCS
145 // Note that these are not virtual.
146 bool is_generation_policy() { return as_generation_policy() != NULL; }
147 bool is_two_generation_policy() { return as_two_generation_policy() != NULL; }
148 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
149 #if INCLUDE_ALL_GCS
150 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
151 bool is_g1_policy() { return as_g1_policy() != NULL; }
152 #else // INCLUDE_ALL_GCS
153 bool is_concurrent_mark_sweep_policy() { return false; }
154 bool is_g1_policy() { return false; }
155 #endif // INCLUDE_ALL_GCS
158 virtual BarrierSet::Name barrier_set_name() = 0;
159 virtual GenRemSet::Name rem_set_name() = 0;
161 // Create the remembered set (to cover the given reserved region,
162 // allowing breaking up into at most "max_covered_regions").
163 virtual GenRemSet* create_rem_set(MemRegion reserved,
164 int max_covered_regions);
166 // This method controls how a collector satisfies a request
167 // for a block of memory. "gc_time_limit_was_exceeded" will
168 // be set to true if the adaptive size policy determine that
169 // an excessive amount of time is being spent doing collections
170 // and caused a NULL to be returned. If a NULL is not returned,
171 // "gc_time_limit_was_exceeded" has an undefined meaning.
172 virtual HeapWord* mem_allocate_work(size_t size,
173 bool is_tlab,
174 bool* gc_overhead_limit_was_exceeded) = 0;
176 // This method controls how a collector handles one or more
177 // of its generations being fully allocated.
178 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
179 // This method controls how a collector handles a metadata allocation
180 // failure.
181 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
182 size_t size,
183 Metaspace::MetadataType mdtype);
185 // Performace Counter support
186 GCPolicyCounters* counters() { return _gc_policy_counters; }
188 // Create the jstat counters for the GC policy. By default, policy's
189 // don't have associated counters, and we complain if this is invoked.
190 virtual void initialize_gc_policy_counters() {
191 ShouldNotReachHere();
192 }
194 virtual CollectorPolicy::Name kind() {
195 return CollectorPolicy::CollectorPolicyKind;
196 }
198 // Returns true if a collector has eden space with soft end.
199 virtual bool has_soft_ended_eden() {
200 return false;
201 }
203 };
205 class ClearedAllSoftRefs : public StackObj {
206 bool _clear_all_soft_refs;
207 CollectorPolicy* _collector_policy;
208 public:
209 ClearedAllSoftRefs(bool clear_all_soft_refs,
210 CollectorPolicy* collector_policy) :
211 _clear_all_soft_refs(clear_all_soft_refs),
212 _collector_policy(collector_policy) {}
214 ~ClearedAllSoftRefs() {
215 if (_clear_all_soft_refs) {
216 _collector_policy->cleared_all_soft_refs();
217 }
218 }
219 };
221 class GenCollectorPolicy : public CollectorPolicy {
222 protected:
223 size_t _min_gen0_size;
224 size_t _initial_gen0_size;
225 size_t _max_gen0_size;
227 GenerationSpec **_generations;
229 // Return true if an allocation should be attempted in the older
230 // generation if it fails in the younger generation. Return
231 // false, otherwise.
232 virtual bool should_try_older_generation_allocation(size_t word_size) const;
234 void initialize_flags();
235 void initialize_size_info();
237 // Try to allocate space by expanding the heap.
238 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
240 // Scale the base_size by NewRation according to
241 // result = base_size / (NewRatio + 1)
242 // and align by min_alignment()
243 size_t scale_by_NewRatio_aligned(size_t base_size);
245 // Bound the value by the given maximum minus the
246 // min_alignment.
247 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
249 public:
250 // Accessors
251 size_t min_gen0_size() { return _min_gen0_size; }
252 void set_min_gen0_size(size_t v) { _min_gen0_size = v; }
253 size_t initial_gen0_size() { return _initial_gen0_size; }
254 void set_initial_gen0_size(size_t v) { _initial_gen0_size = v; }
255 size_t max_gen0_size() { return _max_gen0_size; }
256 void set_max_gen0_size(size_t v) { _max_gen0_size = v; }
258 virtual int number_of_generations() = 0;
260 virtual GenerationSpec **generations() {
261 assert(_generations != NULL, "Sanity check");
262 return _generations;
263 }
265 virtual GenCollectorPolicy* as_generation_policy() { return this; }
267 virtual void initialize_generations() = 0;
269 virtual void initialize_all() {
270 initialize_flags();
271 initialize_size_info();
272 initialize_generations();
273 }
275 HeapWord* mem_allocate_work(size_t size,
276 bool is_tlab,
277 bool* gc_overhead_limit_was_exceeded);
279 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
281 // Adaptive size policy
282 virtual void initialize_size_policy(size_t init_eden_size,
283 size_t init_promo_size,
284 size_t init_survivor_size);
285 };
287 // All of hotspot's current collectors are subtypes of this
288 // class. Currently, these collectors all use the same gen[0],
289 // but have different gen[1] types. If we add another subtype
290 // of CollectorPolicy, this class should be broken out into
291 // its own file.
293 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {
294 protected:
295 size_t _min_gen1_size;
296 size_t _initial_gen1_size;
297 size_t _max_gen1_size;
299 void initialize_flags();
300 void initialize_size_info();
301 void initialize_generations() { ShouldNotReachHere(); }
303 public:
304 // Accessors
305 size_t min_gen1_size() { return _min_gen1_size; }
306 void set_min_gen1_size(size_t v) { _min_gen1_size = v; }
307 size_t initial_gen1_size() { return _initial_gen1_size; }
308 void set_initial_gen1_size(size_t v) { _initial_gen1_size = v; }
309 size_t max_gen1_size() { return _max_gen1_size; }
310 void set_max_gen1_size(size_t v) { _max_gen1_size = v; }
312 // Inherited methods
313 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }
315 int number_of_generations() { return 2; }
316 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; }
317 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
319 virtual CollectorPolicy::Name kind() {
320 return CollectorPolicy::TwoGenerationCollectorPolicyKind;
321 }
323 // Returns true is gen0 sizes were adjusted
324 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,
325 const size_t heap_size, const size_t min_gen1_size);
326 };
328 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {
329 protected:
330 void initialize_generations();
332 public:
333 MarkSweepPolicy();
335 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
337 void initialize_gc_policy_counters();
338 };
340 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP