jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/satbQueue.cpp@399885e13e90 (annotated)

src/share/vm/gc_implementation/g1/satbQueue.cpp@399885e13e90 (annotated)

src/share/vm/gc_implementation/g1/satbQueue.cpp

Fri, 01 May 2015 17:38:12 -0400

author: kbarrett
date: Fri, 01 May 2015 17:38:12 -0400
changeset 7834: 399885e13e90
parent 7833: 0f8f1250fed5
child 7994: 04ff2f6cd0eb
child 9327: f96fcd9e1e1b
permissions: -rw-r--r--

8075215: SATB buffer processing found reclaimed humongous object
Summary: Don't assume SATB buffer entries are valid objects
Reviewed-by: brutisso, ecaspole

 /*
  * Copyright (c) 2001, 2015, 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.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/satbQueue.hpp"
 #include "memory/allocation.inline.hpp"
 #include "memory/sharedHeap.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/safepoint.hpp"
 #include "runtime/thread.hpp"
 #include "runtime/vmThread.hpp"
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 void ObjPtrQueue::flush() {
   // Filter now to possibly save work later.  If filtering empties the
   // buffer then flush_impl can deallocate the buffer.
   filter();
   flush_impl();
 }
 // Return true if a SATB buffer entry refers to an object that
 // requires marking.
 //
 // The entry must point into the G1 heap.  In particular, it must not
 // be a NULL pointer.  NULL pointers are pre-filtered and never
 // inserted into a SATB buffer.
 //
 // An entry that is below the NTAMS pointer for the containing heap
 // region requires marking. Such an entry must point to a valid object.
 //
 // An entry that is at least the NTAMS pointer for the containing heap
 // region might be any of the following, none of which should be marked.
 //
 // * A reference to an object allocated since marking started.
 //   According to SATB, such objects are implicitly kept live and do
 //   not need to be dealt with via SATB buffer processing.
 //
 // * A reference to a young generation object. Young objects are
 //   handled separately and are not marked by concurrent marking.
 //
 // * A stale reference to a young generation object. If a young
 //   generation object reference is recorded and not filtered out
 //   before being moved by a young collection, the reference becomes
 //   stale.
 //
 // * A stale reference to an eagerly reclaimed humongous object.  If a
 //   humongous object is recorded and then reclaimed, the reference
 //   becomes stale.
 //
 // The stale reference cases are implicitly handled by the NTAMS
 // comparison. Because of the possibility of stale references, buffer
 // processing must be somewhat circumspect and not assume entries
 // in an unfiltered buffer refer to valid objects.
 inline bool requires_marking(const void* entry, G1CollectedHeap* heap) {
   // Includes rejection of NULL pointers.
   assert(heap->is_in_reserved(entry),
          err_msg("Non-heap pointer in SATB buffer: " PTR_FORMAT, p2i(entry)));
   HeapRegion* region = heap->heap_region_containing_raw(entry);
   assert(region != NULL, err_msg("No region for " PTR_FORMAT, p2i(entry)));
   if (entry >= region->next_top_at_mark_start()) {
     return false;
   }
   assert(((oop)entry)->is_oop(true /* ignore mark word */),
          err_msg("Invalid oop in SATB buffer: " PTR_FORMAT, p2i(entry)));
   return true;
 }
 // This method removes entries from a SATB buffer that will not be
 // useful to the concurrent marking threads.  Entries are retained if
 // they require marking and are not already marked. Retained entries
 // are compacted toward the top of the buffer.
 void ObjPtrQueue::filter() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   void** buf = _buf;
   size_t sz = _sz;
   if (buf == NULL) {
     // nothing to do
     return;
   }
   // Used for sanity checking at the end of the loop.
   debug_only(size_t entries = 0; size_t retained = 0;)
   size_t i = sz;
   size_t new_index = sz;
   while (i > _index) {
     assert(i > 0, "we should have at least one more entry to process");
     i -= oopSize;
     debug_only(entries += 1;)
     void** p = &buf[byte_index_to_index((int) i)];
     void* entry = *p;
     // NULL the entry so that unused parts of the buffer contain NULLs
     // at the end. If we are going to retain it we will copy it to its
     // final place. If we have retained all entries we have visited so
     // far, we'll just end up copying it to the same place.
     *p = NULL;
     if (requires_marking(entry, g1h) && !g1h->isMarkedNext((oop)entry)) {
       assert(new_index > 0, "we should not have already filled up the buffer");
       new_index -= oopSize;
       assert(new_index >= i,
              "new_index should never be below i, as we alwaysr compact 'up'");
       void** new_p = &buf[byte_index_to_index((int) new_index)];
       assert(new_p >= p, "the destination location should never be below "
              "the source as we always compact 'up'");
       assert(*new_p == NULL,
              "we should have already cleared the destination location");
       *new_p = entry;
       debug_only(retained += 1;)
     }
   }
 #ifdef ASSERT
   size_t entries_calc = (sz - _index) / oopSize;
   assert(entries == entries_calc, "the number of entries we counted "
          "should match the number of entries we calculated");
   size_t retained_calc = (sz - new_index) / oopSize;
   assert(retained == retained_calc, "the number of retained entries we counted "
          "should match the number of retained entries we calculated");
 #endif // ASSERT
   _index = new_index;
 }
 // This method will first apply the above filtering to the buffer. If
 // post-filtering a large enough chunk of the buffer has been cleared
 // we can re-use the buffer (instead of enqueueing it) and we can just
 // allow the mutator to carry on executing using the same buffer
 // instead of replacing it.
 bool ObjPtrQueue::should_enqueue_buffer() {
   assert(_lock == NULL || _lock->owned_by_self(),
          "we should have taken the lock before calling this");
   // If G1SATBBufferEnqueueingThresholdPercent == 0 we could skip filtering.
   // This method should only be called if there is a non-NULL buffer
   // that is full.
   assert(_index == 0, "pre-condition");
   assert(_buf != NULL, "pre-condition");
   filter();
   size_t sz = _sz;
   size_t all_entries = sz / oopSize;
   size_t retained_entries = (sz - _index) / oopSize;
   size_t perc = retained_entries * 100 / all_entries;
   bool should_enqueue = perc > (size_t) G1SATBBufferEnqueueingThresholdPercent;
   return should_enqueue;
 }
 void ObjPtrQueue::apply_closure_and_empty(SATBBufferClosure* cl) {
   assert(SafepointSynchronize::is_at_safepoint(),
          "SATB queues must only be processed at safepoints");
   if (_buf != NULL) {
     assert(_index % sizeof(void*) == 0, "invariant");
     assert(_sz % sizeof(void*) == 0, "invariant");
     assert(_index <= _sz, "invariant");
     cl->do_buffer(_buf + byte_index_to_index((int)_index),
                   byte_index_to_index((int)(_sz - _index)));
     _index = _sz;
   }
 }
 #ifndef PRODUCT
 // Helpful for debugging
 void ObjPtrQueue::print(const char* name) {
   print(name, _buf, _index, _sz);
 }
 void ObjPtrQueue::print(const char* name,
                         void** buf, size_t index, size_t sz) {
   gclog_or_tty->print_cr("  SATB BUFFER [%s] buf: "PTR_FORMAT" "
                          "index: "SIZE_FORMAT" sz: "SIZE_FORMAT,
                          name, buf, index, sz);
 }
 #endif // PRODUCT
 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 #endif // _MSC_VER
 SATBMarkQueueSet::SATBMarkQueueSet() :
   PtrQueueSet(),
   _shared_satb_queue(this, true /*perm*/) { }
 void SATBMarkQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock,
                                   int process_completed_threshold,
                                   Mutex* lock) {
   PtrQueueSet::initialize(cbl_mon, fl_lock, process_completed_threshold, -1);
   _shared_satb_queue.set_lock(lock);
 }
 void SATBMarkQueueSet::handle_zero_index_for_thread(JavaThread* t) {
   t->satb_mark_queue().handle_zero_index();
 }
 #ifdef ASSERT
 void SATBMarkQueueSet::dump_active_states(bool expected_active) {
   gclog_or_tty->print_cr("Expected SATB active state: %s",
                          expected_active ? "ACTIVE" : "INACTIVE");
   gclog_or_tty->print_cr("Actual SATB active states:");
   gclog_or_tty->print_cr("  Queue set: %s", is_active() ? "ACTIVE" : "INACTIVE");
   for (JavaThread* t = Threads::first(); t; t = t->next()) {
     gclog_or_tty->print_cr("  Thread \"%s\" queue: %s", t->name(),
                            t->satb_mark_queue().is_active() ? "ACTIVE" : "INACTIVE");
   }
   gclog_or_tty->print_cr("  Shared queue: %s",
                          shared_satb_queue()->is_active() ? "ACTIVE" : "INACTIVE");
 }
 void SATBMarkQueueSet::verify_active_states(bool expected_active) {
   // Verify queue set state
   if (is_active() != expected_active) {
     dump_active_states(expected_active);
     guarantee(false, "SATB queue set has an unexpected active state");
   }
   // Verify thread queue states
   for (JavaThread* t = Threads::first(); t; t = t->next()) {
     if (t->satb_mark_queue().is_active() != expected_active) {
       dump_active_states(expected_active);
       guarantee(false, "Thread SATB queue has an unexpected active state");
     }
   }
   // Verify shared queue state
   if (shared_satb_queue()->is_active() != expected_active) {
     dump_active_states(expected_active);
     guarantee(false, "Shared SATB queue has an unexpected active state");
   }
 }
 #endif // ASSERT
 void SATBMarkQueueSet::set_active_all_threads(bool active, bool expected_active) {
   assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
 #ifdef ASSERT
   verify_active_states(expected_active);
 #endif // ASSERT
   _all_active = active;
   for (JavaThread* t = Threads::first(); t; t = t->next()) {
     t->satb_mark_queue().set_active(active);
   }
   shared_satb_queue()->set_active(active);
 }
 void SATBMarkQueueSet::filter_thread_buffers() {
   for(JavaThread* t = Threads::first(); t; t = t->next()) {
     t->satb_mark_queue().filter();
   }
   shared_satb_queue()->filter();
 }
 bool SATBMarkQueueSet::apply_closure_to_completed_buffer(SATBBufferClosure* cl) {
   BufferNode* nd = NULL;
   {
     MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
     if (_completed_buffers_head != NULL) {
       nd = _completed_buffers_head;
       _completed_buffers_head = nd->next();
       if (_completed_buffers_head == NULL) _completed_buffers_tail = NULL;
       _n_completed_buffers--;
       if (_n_completed_buffers == 0) _process_completed = false;
     }
   }
   if (nd != NULL) {
     void **buf = BufferNode::make_buffer_from_node(nd);
     // Skip over NULL entries at beginning (e.g. push end) of buffer.
     // Filtering can result in non-full completed buffers; see
     // should_enqueue_buffer.
     assert(_sz % sizeof(void*) == 0, "invariant");
     size_t limit = ObjPtrQueue::byte_index_to_index((int)_sz);
     for (size_t i = 0; i < limit; ++i) {
       if (buf[i] != NULL) {
         // Found the end of the block of NULLs; process the remainder.
         cl->do_buffer(buf + i, limit - i);
         break;
       }
     }
     deallocate_buffer(buf);
     return true;
   } else {
     return false;
   }
 }
 #ifndef PRODUCT
 // Helpful for debugging
 #define SATB_PRINTER_BUFFER_SIZE 256
 void SATBMarkQueueSet::print_all(const char* msg) {
   char buffer[SATB_PRINTER_BUFFER_SIZE];
   assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
   gclog_or_tty->cr();
   gclog_or_tty->print_cr("SATB BUFFERS [%s]", msg);
   BufferNode* nd = _completed_buffers_head;
   int i = 0;
   while (nd != NULL) {
     void** buf = BufferNode::make_buffer_from_node(nd);
     jio_snprintf(buffer, SATB_PRINTER_BUFFER_SIZE, "Enqueued: %d", i);
     ObjPtrQueue::print(buffer, buf, 0, _sz);
     nd = nd->next();
     i += 1;
   }
   for (JavaThread* t = Threads::first(); t; t = t->next()) {
     jio_snprintf(buffer, SATB_PRINTER_BUFFER_SIZE, "Thread: %s", t->name());
     t->satb_mark_queue().print(buffer);
   }
   shared_satb_queue()->print("Shared");
   gclog_or_tty->cr();
 }
 #endif // PRODUCT
 void SATBMarkQueueSet::abandon_partial_marking() {
   BufferNode* buffers_to_delete = NULL;
   {
     MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
     while (_completed_buffers_head != NULL) {
       BufferNode* nd = _completed_buffers_head;
       _completed_buffers_head = nd->next();
       nd->set_next(buffers_to_delete);
       buffers_to_delete = nd;
     }
     _completed_buffers_tail = NULL;
     _n_completed_buffers = 0;
     DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
   }
   while (buffers_to_delete != NULL) {
     BufferNode* nd = buffers_to_delete;
     buffers_to_delete = nd->next();
     deallocate_buffer(BufferNode::make_buffer_from_node(nd));
   }
   assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
   // So we can safely manipulate these queues.
   for (JavaThread* t = Threads::first(); t; t = t->next()) {
     t->satb_mark_queue().reset();
   }
  shared_satb_queue()->reset();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/satbQueue.cpp@399885e13e90 (annotated)

src/share/vm/gc_implementation/g1/satbQueue.cpp