Mon, 29 Apr 2013 16:13:57 -0400
8011773: Some tests on Interned String crashed JVM with OOM
Summary: Instead of terminating the VM, throw OutOfMemoryError exceptions.
Reviewed-by: coleenp, dholmes
1 /*
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25 #include "precompiled.hpp"
26 #include "classfile/javaClasses.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc_interface/collectedHeap.inline.hpp"
33 #include "memory/genCollectedHeap.hpp"
34 #include "memory/genMarkSweep.hpp"
35 #include "memory/genOopClosures.inline.hpp"
36 #include "memory/generation.inline.hpp"
37 #include "memory/modRefBarrierSet.hpp"
38 #include "memory/referencePolicy.hpp"
39 #include "memory/space.hpp"
40 #include "oops/instanceRefKlass.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "prims/jvmtiExport.hpp"
43 #include "runtime/fprofiler.hpp"
44 #include "runtime/handles.inline.hpp"
45 #include "runtime/synchronizer.hpp"
46 #include "runtime/thread.inline.hpp"
47 #include "runtime/vmThread.hpp"
48 #include "utilities/copy.hpp"
49 #include "utilities/events.hpp"
51 void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,
52 bool clear_all_softrefs) {
53 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
55 GenCollectedHeap* gch = GenCollectedHeap::heap();
56 #ifdef ASSERT
57 if (gch->collector_policy()->should_clear_all_soft_refs()) {
58 assert(clear_all_softrefs, "Policy should have been checked earlier");
59 }
60 #endif
62 // hook up weak ref data so it can be used during Mark-Sweep
63 assert(ref_processor() == NULL, "no stomping");
64 assert(rp != NULL, "should be non-NULL");
65 _ref_processor = rp;
66 rp->setup_policy(clear_all_softrefs);
68 TraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, gclog_or_tty);
70 // When collecting the permanent generation Method*s may be moving,
71 // so we either have to flush all bcp data or convert it into bci.
72 CodeCache::gc_prologue();
73 Threads::gc_prologue();
75 // Increment the invocation count
76 _total_invocations++;
78 // Capture heap size before collection for printing.
79 size_t gch_prev_used = gch->used();
81 // Some of the card table updates below assume that the perm gen is
82 // also being collected.
83 assert(level == gch->n_gens() - 1,
84 "All generations are being collected, ergo perm gen too.");
86 // Capture used regions for each generation that will be
87 // subject to collection, so that card table adjustments can
88 // be made intelligently (see clear / invalidate further below).
89 gch->save_used_regions(level);
91 allocate_stacks();
93 mark_sweep_phase1(level, clear_all_softrefs);
95 mark_sweep_phase2();
97 // Don't add any more derived pointers during phase3
98 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
99 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
101 mark_sweep_phase3(level);
103 mark_sweep_phase4();
105 restore_marks();
107 // Set saved marks for allocation profiler (and other things? -- dld)
108 // (Should this be in general part?)
109 gch->save_marks();
111 deallocate_stacks();
113 // If compaction completely evacuated all generations younger than this
114 // one, then we can clear the card table. Otherwise, we must invalidate
115 // it (consider all cards dirty). In the future, we might consider doing
116 // compaction within generations only, and doing card-table sliding.
117 bool all_empty = true;
118 for (int i = 0; all_empty && i < level; i++) {
119 Generation* g = gch->get_gen(i);
120 all_empty = all_empty && gch->get_gen(i)->used() == 0;
121 }
122 GenRemSet* rs = gch->rem_set();
123 // Clear/invalidate below make use of the "prev_used_regions" saved earlier.
124 if (all_empty) {
125 // We've evacuated all generations below us.
126 Generation* g = gch->get_gen(level);
127 rs->clear_into_younger(g);
128 } else {
129 // Invalidate the cards corresponding to the currently used
130 // region and clear those corresponding to the evacuated region
131 // of all generations just collected (i.e. level and younger).
132 rs->invalidate_or_clear(gch->get_gen(level),
133 true /* younger */);
134 }
136 Threads::gc_epilogue();
137 CodeCache::gc_epilogue();
138 JvmtiExport::gc_epilogue();
140 if (PrintGC && !PrintGCDetails) {
141 gch->print_heap_change(gch_prev_used);
142 }
144 // refs processing: clean slate
145 _ref_processor = NULL;
147 // Update heap occupancy information which is used as
148 // input to soft ref clearing policy at the next gc.
149 Universe::update_heap_info_at_gc();
151 // Update time of last gc for all generations we collected
152 // (which curently is all the generations in the heap).
153 // We need to use a monotonically non-deccreasing time in ms
154 // or we will see time-warp warnings and os::javaTimeMillis()
155 // does not guarantee monotonicity.
156 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
157 gch->update_time_of_last_gc(now);
158 }
160 void GenMarkSweep::allocate_stacks() {
161 GenCollectedHeap* gch = GenCollectedHeap::heap();
162 // Scratch request on behalf of oldest generation; will do no
163 // allocation.
164 ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0);
166 // $$$ To cut a corner, we'll only use the first scratch block, and then
167 // revert to malloc.
168 if (scratch != NULL) {
169 _preserved_count_max =
170 scratch->num_words * HeapWordSize / sizeof(PreservedMark);
171 } else {
172 _preserved_count_max = 0;
173 }
175 _preserved_marks = (PreservedMark*)scratch;
176 _preserved_count = 0;
177 }
180 void GenMarkSweep::deallocate_stacks() {
181 if (!UseG1GC) {
182 GenCollectedHeap* gch = GenCollectedHeap::heap();
183 gch->release_scratch();
184 }
186 _preserved_mark_stack.clear(true);
187 _preserved_oop_stack.clear(true);
188 _marking_stack.clear();
189 _objarray_stack.clear(true);
190 }
192 void GenMarkSweep::mark_sweep_phase1(int level,
193 bool clear_all_softrefs) {
194 // Recursively traverse all live objects and mark them
195 TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
196 trace(" 1");
198 GenCollectedHeap* gch = GenCollectedHeap::heap();
200 // Because follow_root_closure is created statically, cannot
201 // use OopsInGenClosure constructor which takes a generation,
202 // as the Universe has not been created when the static constructors
203 // are run.
204 follow_root_closure.set_orig_generation(gch->get_gen(level));
206 // Need new claim bits before marking starts.
207 ClassLoaderDataGraph::clear_claimed_marks();
209 gch->gen_process_strong_roots(level,
210 false, // Younger gens are not roots.
211 true, // activate StrongRootsScope
212 false, // not scavenging
213 SharedHeap::SO_SystemClasses,
214 &follow_root_closure,
215 true, // walk code active on stacks
216 &follow_root_closure,
217 &follow_klass_closure);
219 // Process reference objects found during marking
220 {
221 ref_processor()->setup_policy(clear_all_softrefs);
222 ref_processor()->process_discovered_references(
223 &is_alive, &keep_alive, &follow_stack_closure, NULL);
224 }
226 // Follow system dictionary roots and unload classes
227 bool purged_class = SystemDictionary::do_unloading(&is_alive);
229 // Follow code cache roots
230 CodeCache::do_unloading(&is_alive, purged_class);
231 follow_stack(); // Flush marking stack
233 // Update subklass/sibling/implementor links of live klasses
234 Klass::clean_weak_klass_links(&is_alive);
235 assert(_marking_stack.is_empty(), "just drained");
237 // Visit interned string tables and delete unmarked oops
238 StringTable::unlink(&is_alive);
239 // Clean up unreferenced symbols in symbol table.
240 SymbolTable::unlink();
242 assert(_marking_stack.is_empty(), "stack should be empty by now");
243 }
246 void GenMarkSweep::mark_sweep_phase2() {
247 // Now all live objects are marked, compute the new object addresses.
249 // It is imperative that we traverse perm_gen LAST. If dead space is
250 // allowed a range of dead object may get overwritten by a dead int
251 // array. If perm_gen is not traversed last a Klass* may get
252 // overwritten. This is fine since it is dead, but if the class has dead
253 // instances we have to skip them, and in order to find their size we
254 // need the Klass*!
255 //
256 // It is not required that we traverse spaces in the same order in
257 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
258 // tracking expects us to do so. See comment under phase4.
260 GenCollectedHeap* gch = GenCollectedHeap::heap();
262 TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
263 trace("2");
265 gch->prepare_for_compaction();
266 }
268 class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure {
269 public:
270 void do_generation(Generation* gen) {
271 gen->adjust_pointers();
272 }
273 };
275 void GenMarkSweep::mark_sweep_phase3(int level) {
276 GenCollectedHeap* gch = GenCollectedHeap::heap();
278 // Adjust the pointers to reflect the new locations
279 TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
280 trace("3");
282 // Need new claim bits for the pointer adjustment tracing.
283 ClassLoaderDataGraph::clear_claimed_marks();
285 // Because the two closures below are created statically, cannot
286 // use OopsInGenClosure constructor which takes a generation,
287 // as the Universe has not been created when the static constructors
288 // are run.
289 adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level));
290 adjust_pointer_closure.set_orig_generation(gch->get_gen(level));
292 gch->gen_process_strong_roots(level,
293 false, // Younger gens are not roots.
294 true, // activate StrongRootsScope
295 false, // not scavenging
296 SharedHeap::SO_AllClasses,
297 &adjust_root_pointer_closure,
298 false, // do not walk code
299 &adjust_root_pointer_closure,
300 &adjust_klass_closure);
302 // Now adjust pointers in remaining weak roots. (All of which should
303 // have been cleared if they pointed to non-surviving objects.)
304 CodeBlobToOopClosure adjust_code_pointer_closure(&adjust_pointer_closure,
305 /*do_marking=*/ false);
306 gch->gen_process_weak_roots(&adjust_root_pointer_closure,
307 &adjust_code_pointer_closure,
308 &adjust_pointer_closure);
310 adjust_marks();
311 GenAdjustPointersClosure blk;
312 gch->generation_iterate(&blk, true);
313 }
315 class GenCompactClosure: public GenCollectedHeap::GenClosure {
316 public:
317 void do_generation(Generation* gen) {
318 gen->compact();
319 }
320 };
322 void GenMarkSweep::mark_sweep_phase4() {
323 // All pointers are now adjusted, move objects accordingly
325 // It is imperative that we traverse perm_gen first in phase4. All
326 // classes must be allocated earlier than their instances, and traversing
327 // perm_gen first makes sure that all Klass*s have moved to their new
328 // location before any instance does a dispatch through it's klass!
330 // The ValidateMarkSweep live oops tracking expects us to traverse spaces
331 // in the same order in phase2, phase3 and phase4. We don't quite do that
332 // here (perm_gen first rather than last), so we tell the validate code
333 // to use a higher index (saved from phase2) when verifying perm_gen.
334 GenCollectedHeap* gch = GenCollectedHeap::heap();
336 TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
337 trace("4");
339 GenCompactClosure blk;
340 gch->generation_iterate(&blk, true);
341 }