Mercurial > hg > graal-jvmci-8

comparison src/share/vm/memory/referenceProcessor.hpp @ 453:c96030fff130

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
6684579: SoftReference processing can be made more efficient Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not. Reviewed-by: jmasa
author ysr
date Thu, 20 Nov 2008 16:56:09 -0800
parents 1ee8caae33af
children 27a80744a83b
comparison
equal deleted inserted replaced
452:00b023ae2d78 453:c96030fff130
21 * have any questions. 21 * have any questions.
22 * 22 *
23 */ 23 */
24 24
25 // ReferenceProcessor class encapsulates the per-"collector" processing 25 // ReferenceProcessor class encapsulates the per-"collector" processing
26 // of "weak" references for GC. The interface is useful for supporting 26 // of java.lang.Reference objects for GC. The interface is useful for supporting
27 // a generational abstraction, in particular when there are multiple 27 // a generational abstraction, in particular when there are multiple
28 // generations that are being independently collected -- possibly 28 // generations that are being independently collected -- possibly
29 // concurrently and/or incrementally. Note, however, that the 29 // concurrently and/or incrementally. Note, however, that the
30 // ReferenceProcessor class abstracts away from a generational setting 30 // ReferenceProcessor class abstracts away from a generational setting
31 // by using only a heap interval (called "span" below), thus allowing 31 // by using only a heap interval (called "span" below), thus allowing
73 // helps the reference processor determine the reachability 73 // helps the reference processor determine the reachability
74 // of an oop (the field is currently initialized to NULL for 74 // of an oop (the field is currently initialized to NULL for
75 // all collectors but the CMS collector). 75 // all collectors but the CMS collector).
76 BoolObjectClosure* _is_alive_non_header; 76 BoolObjectClosure* _is_alive_non_header;
77 77
78 // Soft ref clearing policies
79 // . the default policy
80 static ReferencePolicy* _default_soft_ref_policy;
81 // . the "clear all" policy
82 static ReferencePolicy* _always_clear_soft_ref_policy;
83 // . the current policy below is either one of the above
84 ReferencePolicy* _current_soft_ref_policy;
85
78 // The discovered ref lists themselves 86 // The discovered ref lists themselves
79 87
80 // The MT'ness degree of the queues below 88 // The MT'ness degree of the queues below
81 int _num_q; 89 int _num_q;
82 // Arrays of lists of oops, one per thread 90 // Arrays of lists of oops, one per thread
88 public: 96 public:
89 int num_q() { return _num_q; } 97 int num_q() { return _num_q; }
90 DiscoveredList* discovered_soft_refs() { return _discoveredSoftRefs; } 98 DiscoveredList* discovered_soft_refs() { return _discoveredSoftRefs; }
91 static oop sentinel_ref() { return _sentinelRef; } 99 static oop sentinel_ref() { return _sentinelRef; }
92 static oop* adr_sentinel_ref() { return &_sentinelRef; } 100 static oop* adr_sentinel_ref() { return &_sentinelRef; }
101 ReferencePolicy* snap_policy(bool always_clear) {
102 _current_soft_ref_policy = always_clear ?
103 _always_clear_soft_ref_policy : _default_soft_ref_policy;
104 _current_soft_ref_policy->snap(); // snapshot the policy threshold
105 return _current_soft_ref_policy;
106 }
93 107
94 public: 108 public:
95 // Process references with a certain reachability level. 109 // Process references with a certain reachability level.
96 void process_discovered_reflist(DiscoveredList refs_lists[], 110 void process_discovered_reflist(DiscoveredList refs_lists[],
97 ReferencePolicy* policy, 111 ReferencePolicy* policy,
295 309
296 // Discover a Reference object, using appropriate discovery criteria 310 // Discover a Reference object, using appropriate discovery criteria
297 bool discover_reference(oop obj, ReferenceType rt); 311 bool discover_reference(oop obj, ReferenceType rt);
298 312
299 // Process references found during GC (called by the garbage collector) 313 // Process references found during GC (called by the garbage collector)
300 void process_discovered_references(ReferencePolicy* policy, 314 void process_discovered_references(BoolObjectClosure* is_alive,
301 BoolObjectClosure* is_alive,
302 OopClosure* keep_alive, 315 OopClosure* keep_alive,
303 VoidClosure* complete_gc, 316 VoidClosure* complete_gc,
304 AbstractRefProcTaskExecutor* task_executor); 317 AbstractRefProcTaskExecutor* task_executor);
305 318
306 public: 319 public: