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comparison src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 283:9199f248b0ee

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6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning Summary: When an object array overflows during precleaning, we should have been marking the entire array dirty, not just its first card. Reviewed-by: jmasa, poonam, tonyp
author ysr
date Thu, 14 Aug 2008 17:58:35 -0700
parents 818a18cd69a8
children ebeb6490b814 1ee8caae33af
comparison
equal deleted inserted replaced
277:79276d1b7e50 283:9199f248b0ee
6865 // We re-dirty the cards on which this object lies and increase 6865 // We re-dirty the cards on which this object lies and increase
6866 // the _threshold so that we'll come back to scan this object 6866 // the _threshold so that we'll come back to scan this object
6867 // during the preclean or remark phase. (CMSCleanOnEnter) 6867 // during the preclean or remark phase. (CMSCleanOnEnter)
6868 if (CMSCleanOnEnter) { 6868 if (CMSCleanOnEnter) {
6869 size_t sz = _collector->block_size_using_printezis_bits(addr); 6869 size_t sz = _collector->block_size_using_printezis_bits(addr);
6870 HeapWord* start_card_addr = (HeapWord*)round_down(
6871 (intptr_t)addr, CardTableModRefBS::card_size);
6872 HeapWord* end_card_addr = (HeapWord*)round_to( 6870 HeapWord* end_card_addr = (HeapWord*)round_to(
6873 (intptr_t)(addr+sz), CardTableModRefBS::card_size); 6871 (intptr_t)(addr+sz), CardTableModRefBS::card_size);
6874 MemRegion redirty_range = MemRegion(start_card_addr, end_card_addr); 6872 MemRegion redirty_range = MemRegion(addr, end_card_addr);
6875 assert(!redirty_range.is_empty(), "Arithmetical tautology"); 6873 assert(!redirty_range.is_empty(), "Arithmetical tautology");
6876 // Bump _threshold to end_card_addr; note that 6874 // Bump _threshold to end_card_addr; note that
6877 // _threshold cannot possibly exceed end_card_addr, anyhow. 6875 // _threshold cannot possibly exceed end_card_addr, anyhow.
6878 // This prevents future clearing of the card as the scan proceeds 6876 // This prevents future clearing of the card as the scan proceeds
6879 // to the right. 6877 // to the right.
7458 simulate_overflow = true; 7456 simulate_overflow = true;
7459 } 7457 }
7460 ) 7458 )
7461 if (simulate_overflow || !_mark_stack->push(obj)) { 7459 if (simulate_overflow || !_mark_stack->push(obj)) {
7462 if (_concurrent_precleaning) { 7460 if (_concurrent_precleaning) {
7463 // During precleaning we can just dirty the appropriate card 7461 // During precleaning we can just dirty the appropriate card(s)
7464 // in the mod union table, thus ensuring that the object remains 7462 // in the mod union table, thus ensuring that the object remains
7465 // in the grey set and continue. Note that no one can be intefering 7463 // in the grey set and continue. In the case of object arrays
7466 // with us in this action of dirtying the mod union table, so 7464 // we need to dirty all of the cards that the object spans,
7467 // no locking is required. 7465 // since the rescan of object arrays will be limited to the
7468 _mod_union_table->mark(addr); 7466 // dirty cards.
7467 // Note that no one can be intefering with us in this action
7468 // of dirtying the mod union table, so no locking or atomics
7469 // are required.
7470 if (obj->is_objArray()) {
7471 size_t sz = obj->size();
7472 HeapWord* end_card_addr = (HeapWord*)round_to(
7473 (intptr_t)(addr+sz), CardTableModRefBS::card_size);
7474 MemRegion redirty_range = MemRegion(addr, end_card_addr);
7475 assert(!redirty_range.is_empty(), "Arithmetical tautology");
7476 _mod_union_table->mark_range(redirty_range);
7477 } else {
7478 _mod_union_table->mark(addr);
7479 }
7469 _collector->_ser_pmc_preclean_ovflw++; 7480 _collector->_ser_pmc_preclean_ovflw++;
7470 } else { 7481 } else {
7471 // During the remark phase, we need to remember this oop 7482 // During the remark phase, we need to remember this oop
7472 // in the overflow list. 7483 // in the overflow list.
7473 _collector->push_on_overflow_list(obj); 7484 _collector->push_on_overflow_list(obj);