6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
Summary: Use _max_num_q = max(discovery_degree, processing_degree), and let balance_queues() redistribute from discovery_degree to processing_degree of queues. This should also allow a more dynamic and flexible parallelism policy in the future.
Reviewed-by: jmasa, johnc
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#ifndef SHARE_VM_MEMORY_SPACE_INLINE_HPP
#define SHARE_VM_MEMORY_SPACE_INLINE_HPP
#include "gc_interface/collectedHeap.hpp"
#include "memory/space.hpp"
#include "memory/universe.hpp"
#include "runtime/safepoint.hpp"
inline HeapWord* Space::block_start(const void* p) {
return block_start_const(p);
}
inline HeapWord* OffsetTableContigSpace::allocate(size_t size) {
HeapWord* res = ContiguousSpace::allocate(size);
if (res != NULL) {
_offsets.alloc_block(res, size);
}
return res;
}
// Because of the requirement of keeping "_offsets" up to date with the
// allocations, we sequentialize these with a lock. Therefore, best if
// this is used for larger LAB allocations only.
inline HeapWord* OffsetTableContigSpace::par_allocate(size_t size) {
MutexLocker x(&_par_alloc_lock);
// This ought to be just "allocate", because of the lock above, but that
// ContiguousSpace::allocate asserts that either the allocating thread
// holds the heap lock or it is the VM thread and we're at a safepoint.
// The best I (dld) could figure was to put a field in ContiguousSpace
// meaning "locking at safepoint taken care of", and set/reset that
// here. But this will do for now, especially in light of the comment
// above. Perhaps in the future some lock-free manner of keeping the
// coordination.
HeapWord* res = ContiguousSpace::par_allocate(size);
if (res != NULL) {
_offsets.alloc_block(res, size);
}
return res;
}
inline HeapWord*
OffsetTableContigSpace::block_start_const(const void* p) const {
return _offsets.block_start(p);
}
inline HeapWord* ContiguousSpace::concurrent_iteration_safe_limit()
{
assert(_concurrent_iteration_safe_limit <= top(),
"_concurrent_iteration_safe_limit update missed");
return _concurrent_iteration_safe_limit;
}
inline void ContiguousSpace::set_concurrent_iteration_safe_limit(HeapWord* new_limit)
{
assert(new_limit <= top(), "uninitialized objects in the safe range");
_concurrent_iteration_safe_limit = new_limit;
}
#endif // SHARE_VM_MEMORY_SPACE_INLINE_HPP