Tue, 14 Jan 2014 16:40:33 +0100
8032379: Remove the is_scavenging flag to process_strong_roots
Summary: Refactor the strong root processing to avoid using a boolean in addition to the ScanOption enum.
Reviewed-by: stefank, tschatzl, ehelin, jmasa
1 /*
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25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_interface/collectedHeap.inline.hpp"
30 #include "memory/sharedHeap.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/fprofiler.hpp"
33 #include "runtime/java.hpp"
34 #include "services/management.hpp"
35 #include "utilities/copy.hpp"
36 #include "utilities/workgroup.hpp"
38 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
40 SharedHeap* SharedHeap::_sh;
42 // The set of potentially parallel tasks in strong root scanning.
43 enum SH_process_strong_roots_tasks {
44 SH_PS_Universe_oops_do,
45 SH_PS_JNIHandles_oops_do,
46 SH_PS_ObjectSynchronizer_oops_do,
47 SH_PS_FlatProfiler_oops_do,
48 SH_PS_Management_oops_do,
49 SH_PS_SystemDictionary_oops_do,
50 SH_PS_ClassLoaderDataGraph_oops_do,
51 SH_PS_jvmti_oops_do,
52 SH_PS_CodeCache_oops_do,
53 // Leave this one last.
54 SH_PS_NumElements
55 };
57 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
58 CollectedHeap(),
59 _collector_policy(policy_),
60 _rem_set(NULL),
61 _strong_roots_parity(0),
62 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
63 _workers(NULL)
64 {
65 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
66 vm_exit_during_initialization("Failed necessary allocation.");
67 }
68 _sh = this; // ch is static, should be set only once.
69 if ((UseParNewGC ||
70 (UseConcMarkSweepGC && (CMSParallelInitialMarkEnabled ||
71 CMSParallelRemarkEnabled)) ||
72 UseG1GC) &&
73 ParallelGCThreads > 0) {
74 _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
75 /* are_GC_task_threads */true,
76 /* are_ConcurrentGC_threads */false);
77 if (_workers == NULL) {
78 vm_exit_during_initialization("Failed necessary allocation.");
79 } else {
80 _workers->initialize_workers();
81 }
82 }
83 }
85 int SharedHeap::n_termination() {
86 return _process_strong_tasks->n_threads();
87 }
89 void SharedHeap::set_n_termination(int t) {
90 _process_strong_tasks->set_n_threads(t);
91 }
93 bool SharedHeap::heap_lock_held_for_gc() {
94 Thread* t = Thread::current();
95 return Heap_lock->owned_by_self()
96 || ( (t->is_GC_task_thread() || t->is_VM_thread())
97 && _thread_holds_heap_lock_for_gc);
98 }
100 void SharedHeap::set_par_threads(uint t) {
101 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
102 _n_par_threads = t;
103 _process_strong_tasks->set_n_threads(t);
104 }
106 #ifdef ASSERT
107 class AssertNonScavengableClosure: public OopClosure {
108 public:
109 virtual void do_oop(oop* p) {
110 assert(!Universe::heap()->is_in_partial_collection(*p),
111 "Referent should not be scavengable."); }
112 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
113 };
114 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
115 #endif
117 void SharedHeap::change_strong_roots_parity() {
118 // Also set the new collection parity.
119 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
120 "Not in range.");
121 _strong_roots_parity++;
122 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
123 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
124 "Not in range.");
125 }
127 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
128 : MarkScope(activate)
129 {
130 if (_active) {
131 outer->change_strong_roots_parity();
132 // Zero the claimed high water mark in the StringTable
133 StringTable::clear_parallel_claimed_index();
134 }
135 }
137 SharedHeap::StrongRootsScope::~StrongRootsScope() {
138 // nothing particular
139 }
141 void SharedHeap::process_strong_roots(bool activate_scope,
142 ScanningOption so,
143 OopClosure* roots,
144 CodeBlobClosure* code_roots,
145 KlassClosure* klass_closure) {
146 StrongRootsScope srs(this, activate_scope);
148 // General strong roots.
149 assert(_strong_roots_parity != 0, "must have called prologue code");
150 // _n_termination for _process_strong_tasks should be set up stream
151 // in a method not running in a GC worker. Otherwise the GC worker
152 // could be trying to change the termination condition while the task
153 // is executing in another GC worker.
154 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
155 Universe::oops_do(roots);
156 }
157 // Global (strong) JNI handles
158 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
159 JNIHandles::oops_do(roots);
161 CLDToOopClosure roots_from_clds(roots);
162 // If we limit class scanning to SO_SystemClasses we need to apply a CLD closure to
163 // CLDs which are strongly reachable from the thread stacks.
164 CLDToOopClosure* roots_from_clds_p = ((so & SO_SystemClasses) ? &roots_from_clds : NULL);
165 // All threads execute this; the individual threads are task groups.
166 if (CollectedHeap::use_parallel_gc_threads()) {
167 Threads::possibly_parallel_oops_do(roots, roots_from_clds_p, code_roots);
168 } else {
169 Threads::oops_do(roots, roots_from_clds_p, code_roots);
170 }
172 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
173 ObjectSynchronizer::oops_do(roots);
174 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
175 FlatProfiler::oops_do(roots);
176 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
177 Management::oops_do(roots);
178 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
179 JvmtiExport::oops_do(roots);
181 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
182 if (so & SO_AllClasses) {
183 SystemDictionary::oops_do(roots);
184 } else if (so & SO_SystemClasses) {
185 SystemDictionary::always_strong_oops_do(roots);
186 } else {
187 fatal("We should always have selected either SO_AllClasses or SO_SystemClasses");
188 }
189 }
191 if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
192 if (so & SO_AllClasses) {
193 ClassLoaderDataGraph::oops_do(roots, klass_closure, /* must_claim */ false);
194 } else if (so & SO_SystemClasses) {
195 ClassLoaderDataGraph::always_strong_oops_do(roots, klass_closure, /* must_claim */ true);
196 }
197 }
199 // All threads execute the following. A specific chunk of buckets
200 // from the StringTable are the individual tasks.
201 if (so & SO_Strings) {
202 if (CollectedHeap::use_parallel_gc_threads()) {
203 StringTable::possibly_parallel_oops_do(roots);
204 } else {
205 StringTable::oops_do(roots);
206 }
207 }
209 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
210 if (so & SO_ScavengeCodeCache) {
211 assert(code_roots != NULL, "must supply closure for code cache");
213 // We only visit parts of the CodeCache when scavenging.
214 CodeCache::scavenge_root_nmethods_do(code_roots);
215 }
216 if (so & SO_AllCodeCache) {
217 assert(code_roots != NULL, "must supply closure for code cache");
219 // CMSCollector uses this to do intermediate-strength collections.
220 // We scan the entire code cache, since CodeCache::do_unloading is not called.
221 CodeCache::blobs_do(code_roots);
222 }
223 // Verify that the code cache contents are not subject to
224 // movement by a scavenging collection.
225 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
226 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
227 }
229 _process_strong_tasks->all_tasks_completed();
230 }
232 class AlwaysTrueClosure: public BoolObjectClosure {
233 public:
234 bool do_object_b(oop p) { return true; }
235 };
236 static AlwaysTrueClosure always_true;
238 void SharedHeap::process_weak_roots(OopClosure* root_closure,
239 CodeBlobClosure* code_roots) {
240 // Global (weak) JNI handles
241 JNIHandles::weak_oops_do(&always_true, root_closure);
243 CodeCache::blobs_do(code_roots);
244 StringTable::oops_do(root_closure);
245 }
247 void SharedHeap::set_barrier_set(BarrierSet* bs) {
248 _barrier_set = bs;
249 // Cached barrier set for fast access in oops
250 oopDesc::set_bs(bs);
251 }
253 void SharedHeap::post_initialize() {
254 CollectedHeap::post_initialize();
255 ref_processing_init();
256 }
258 void SharedHeap::ref_processing_init() {}
260 // Some utilities.
261 void SharedHeap::print_size_transition(outputStream* out,
262 size_t bytes_before,
263 size_t bytes_after,
264 size_t capacity) {
265 out->print(" %d%s->%d%s(%d%s)",
266 byte_size_in_proper_unit(bytes_before),
267 proper_unit_for_byte_size(bytes_before),
268 byte_size_in_proper_unit(bytes_after),
269 proper_unit_for_byte_size(bytes_after),
270 byte_size_in_proper_unit(capacity),
271 proper_unit_for_byte_size(capacity));
272 }