src/hotspot/share/gc/z/zObjArrayAllocator.cpp

*** 23,72 ****
  
  #include "precompiled.hpp"
  #include "gc/z/zThreadLocalData.hpp"
  #include "gc/z/zObjArrayAllocator.hpp"
  #include "gc/z/zUtils.inline.hpp"
- #include "memory/universe.hpp"
  #include "oops/arrayKlass.hpp"
  #include "runtime/interfaceSupport.inline.hpp"
- #include "runtime/handles.hpp"
- #include "runtime/os.hpp"
- #include "utilities/debug.hpp"
- #include "utilities/globalDefinitions.hpp"
- 
- // To avoid delaying safepoints, clearing of arrays is split up in segments
- // with safepoint polling inbetween. However, we can't have a not-yet-cleared
- // array of oops on the heap when we safepoint since the GC will then stumble
- // across uninitialized oops. To avoid this we let an array of oops be an
- // array of a primitive type of the same size until the clearing has completed.
- // A max segment size of 64K was chosen because benchmarking suggests that is
- // offers a good trade-off between allocation time and time-to-safepoint.
- 
- static Klass* substitute_object_array_klass(Klass* klass) {
-   if (!klass->is_objArray_klass()) {
-     return klass;
-   }
- 
-   Klass* const substitute_klass = Universe::longArrayKlassObj();
-   const BasicType type = ArrayKlass::cast(klass)->element_type();
-   const BasicType substitute_type = ArrayKlass::cast(substitute_klass)->element_type();
-   assert(type2aelembytes(type) == type2aelembytes(substitute_type), "Element size mismatch");
-   return substitute_klass;
- }
  
  ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, Thread* thread) :
!     ObjArrayAllocator(substitute_object_array_klass(klass), word_size, length, false /* do_zero */, thread),
!     _final_klass(klass) {}
  
  oop ZObjArrayAllocator::finish(HeapWord* mem) const {
!   // Set mark word and initial klass pointer
    ObjArrayAllocator::finish(mem);
  
!   // Keep the array alive across safepoints, but make it invisible
!   // to the heap itarator until the final klass pointer has been set
    ZThreadLocalData::set_invisible_root(_thread, (oop*)&mem);
  
    const size_t segment_max = ZUtils::bytes_to_words(64 * K);
    const size_t skip = arrayOopDesc::header_size(ArrayKlass::cast(_klass)->element_type());
    size_t remaining = _word_size - skip;
  
    while (remaining > 0) {
--- 23,50 ----
  
  #include "precompiled.hpp"
  #include "gc/z/zThreadLocalData.hpp"
  #include "gc/z/zObjArrayAllocator.hpp"
  #include "gc/z/zUtils.inline.hpp"
  #include "oops/arrayKlass.hpp"
  #include "runtime/interfaceSupport.inline.hpp"
  
  ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, Thread* thread) :
!     ObjArrayAllocator(klass, word_size, length, false /* do_zero */, thread) {}
  
  oop ZObjArrayAllocator::finish(HeapWord* mem) const {
!   // Initialize object header and length field
    ObjArrayAllocator::finish(mem);
  
!   // Keep the array alive across safepoints through an invisible
!   // root. Invisible roots are not visited by the heap itarator
!   // and the marking logic will not attempt to follow its elements.
    ZThreadLocalData::set_invisible_root(_thread, (oop*)&mem);
  
+   // A max segment size of 64K was chosen because microbenchmarking
+   // suggested that it offered a good trade-off between allocation
+   // time and time-to-safepoint
    const size_t segment_max = ZUtils::bytes_to_words(64 * K);
    const size_t skip = arrayOopDesc::header_size(ArrayKlass::cast(_klass)->element_type());
    size_t remaining = _word_size - skip;
  
    while (remaining > 0) {
*** 79,93 ****
        // Safepoint
        ThreadBlockInVM tbivm((JavaThread*)_thread);
      }
    }
  
-   if (_klass != _final_klass) {
-     // Set final klass pointer
-     oopDesc::release_set_klass(mem, _final_klass);
-   }
- 
-   // Make the array visible to the heap iterator
    ZThreadLocalData::clear_invisible_root(_thread);
  
    return oop(mem);
  }
--- 57,65 ----