jdk8-mips64-public/hotspot: comparison src/share/vm/gc

-:a672e43650cc
+:97ba643ea3ed
 /*
-* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 // Concurrent accesss to a SparsePRT must be serialized by some external
 // mutex.
 class SparsePRTIter;
+class SparsePRTCleanupTask;
 class SparsePRT VALUE_OBJ_CLASS_SPEC {
+friend class SparsePRTCleanupTask;
 //  Iterations are done on the _cur hash table, since they only need to
 //  see entries visible at the start of a collection pause.
 //  All other operations are done using the _next hash table.
 RSHashTable* _cur;
 RSHashTable* _next;
 SparsePRT* _next_expanded;
 SparsePRT* next_expanded() { return _next_expanded; }
 void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
+bool should_be_on_expanded_list();
 static SparsePRT* _head_expanded_list;
 public:
 SparsePRT(HeapRegion* hr);
 void init_iterator(SparsePRTIter* sprt_iter);
 static void add_to_expanded_list(SparsePRT* sprt);
 static SparsePRT* get_from_expanded_list();
+// The purpose of these three methods is to help the GC workers
+// during the cleanup pause to recreate the expanded list, purging
+// any tables from it that belong to regions that are freed during
+// cleanup (if we don't purge those tables, there is a race that
+// causes various crashes; see CR 7014261).
+//
+// We chose to recreate the expanded list, instead of purging
+// entries from it by iterating over it, to avoid this serial phase
+// at the end of the cleanup pause.
+//
+// The three methods below work as follows:
+// * reset_for_cleanup_tasks() : Nulls the expanded list head at the
+//   start of the cleanup pause.
+// * do_cleanup_work() : Called by the cleanup workers for every
+//   region that is not free / is being freed by the cleanup
+//   pause. It creates a list of expanded tables whose head / tail
+//   are on the thread-local SparsePRTCleanupTask object.
+// * finish_cleanup_task() : Called by the cleanup workers after
+//   they complete their cleanup task. It adds the local list into
+//   the global expanded list. It assumes that the
+//   ParGCRareEvent_lock is being held to ensure MT-safety.
+static void reset_for_cleanup_tasks();
+void do_cleanup_work(SparsePRTCleanupTask* sprt_cleanup_task);
+static void finish_cleanup_task(SparsePRTCleanupTask* sprt_cleanup_task);
 bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const {
 return _next->contains_card(region_id, card_index);
 }
 };
 class SparsePRTIter: public RSHashTableIter {
 public:
 void init(const SparsePRT* sprt) {
 RSHashTableIter::init(sprt->cur());
 }
 bool has_next(size_t& card_index) {
 return RSHashTableIter::has_next(card_index);
 }
 };
+// This allows each worker during a cleanup pause to create a
+// thread-local list of sparse tables that have been expanded and need
+// to be processed at the beginning of the next GC pause. This lists
+// are concatenated into the single expanded list at the end of the
+// cleanup pause.
+class SparsePRTCleanupTask VALUE_OBJ_CLASS_SPEC {
+private:
+SparsePRT* _head;
+SparsePRT* _tail;
+public:
+SparsePRTCleanupTask() : _head(NULL), _tail(NULL) { }
+void add(SparsePRT* sprt);
+SparsePRT* head() { return _head; }
+SparsePRT* tail() { return _tail; }
+};
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP

comparison: src/share/vm/gc_implementation/g1/sparsePRT.hpp

src/share/vm/gc_implementation/g1/sparsePRT.hpp

Mercurial > jdk8-mips64-public > hotspot / file comparison

comparison: src/share/vm/gc_implementation/g1/sparsePRT.hpp

src/share/vm/gc_implementation/g1/sparsePRT.hpp