< prev index next >

src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp

Print this page
@@ -1,7 +1,8 @@
  /*
   * Copyright (c) 2015, 2020, Red Hat, Inc. All rights reserved.
+  * Copyright Amazon.com Inc. 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.

@@ -38,18 +39,20 @@
  #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
  #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
  #include "gc/shenandoah/shenandoahWorkGroup.hpp"
  #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
  #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
- #include "gc/shenandoah/shenandoahControlThread.hpp"
+ #include "gc/shenandoah/shenandoahGeneration.hpp"
  #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
+ #include "gc/shenandoah/mode/shenandoahMode.hpp"
  #include "oops/compressedOops.inline.hpp"
  #include "oops/oop.inline.hpp"
  #include "runtime/atomic.hpp"
  #include "runtime/javaThread.hpp"
  #include "runtime/prefetch.inline.hpp"
+ #include "runtime/objectMonitor.inline.hpp"
  #include "utilities/copy.hpp"
  #include "utilities/globalDefinitions.hpp"
  
  inline ShenandoahHeap* ShenandoahHeap::heap() {
    return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);

@@ -262,13 +265,21 @@
      }
    }
    return cancelled_gc();
  }
  
- inline void ShenandoahHeap::clear_cancelled_gc() {
+ inline void ShenandoahHeap::clear_cancelled_gc(bool clear_oom_handler) {
    _cancelled_gc.set(CANCELLABLE);
-   _oom_evac_handler.clear();
+   if (_cancel_requested_time > 0) {
+     double cancel_time = os::elapsedTime() - _cancel_requested_time;
+     log_info(gc)("GC cancellation took %.3fs", cancel_time);
+     _cancel_requested_time = 0;
+   }
+ 
+   if (clear_oom_handler) {
+     _oom_evac_handler.clear();
+   }
  }
  
  inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
    assert(UseTLAB, "TLABs should be enabled");
  

@@ -281,14 +292,155 @@
    }
    HeapWord* obj = gclab->allocate(size);
    if (obj != nullptr) {
      return obj;
    }
-   // Otherwise...
    return allocate_from_gclab_slow(thread, size);
  }
  
+ void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
+   // This operates on new copy of an object. This means that the object's mark-word
+   // is thread-local and therefore safe to access. However, when the mark is
+   // displaced (i.e. stack-locked or monitor-locked), then it must be considered
+   // a shared memory location. It can be accessed by other threads.
+   // In particular, a competing evacuating thread can succeed to install its copy
+   // as the forwardee and continue to unlock the object, at which point 'our'
+   // write to the foreign stack-location would potentially over-write random
+   // information on that stack. Writing to a monitor is less problematic,
+   // but still not safe: while the ObjectMonitor would not randomly disappear,
+   // the other thread would also write to the same displaced header location,
+   // possibly leading to increase the age twice.
+   // For all these reasons, we take the conservative approach and not attempt
+   // to increase the age when the header is displaced.
+   markWord w = obj->mark();
+   // The mark-word has been copied from the original object. It can not be
+   // inflating, because inflation can not be interrupted by a safepoint,
+   // and after a safepoint, a Java thread would first have to successfully
+   // evacuate the object before it could inflate the monitor.
+   assert(!w.is_being_inflated() || LockingMode == LM_LIGHTWEIGHT, "must not inflate monitor before evacuation of object succeeds");
+   // It is possible that we have copied the object after another thread has
+   // already successfully completed evacuation. While harmless (we would never
+   // publish our copy), don't even attempt to modify the age when that
+   // happens.
+   if (!w.has_displaced_mark_helper() && !w.is_marked()) {
+     w = w.set_age(MIN2(markWord::max_age, w.age() + additional_age));
+     obj->set_mark(w);
+   }
+ }
+ 
+ // Return the object's age, or a sentinel value when the age can't
+ // necessarily be determined because of concurrent locking by the
+ // mutator
+ uint ShenandoahHeap::get_object_age(oop obj) {
+   // This is impossible to do unless we "freeze" ABA-type oscillations
+   // With Lilliput, we can do this more easily.
+   markWord w = obj->mark();
+   assert(!w.is_marked(), "must not be forwarded");
+   if (w.has_monitor()) {
+     w = w.monitor()->header();
+   } else if (w.is_being_inflated() || w.has_displaced_mark_helper()) {
+     // Informs caller that we aren't able to determine the age
+     return markWord::max_age + 1; // sentinel
+   }
+   assert(w.age() <= markWord::max_age, "Impossible!");
+   return w.age();
+ }
+ 
+ bool ShenandoahHeap::is_in(const void* p) const {
+   HeapWord* heap_base = (HeapWord*) base();
+   HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
+   return p >= heap_base && p < last_region_end;
+ }
+ 
+ inline bool ShenandoahHeap::is_in_active_generation(oop obj) const {
+   if (!mode()->is_generational()) {
+     // everything is the same single generation
+     assert(is_in(obj), "Otherwise shouldn't return true below");
+     return true;
+   }
+ 
+   ShenandoahGeneration* const gen = active_generation();
+ 
+   if (gen == nullptr) {
+     // no collection is happening: only expect this to be called
+     // when concurrent processing is active, but that could change
+     return false;
+   }
+ 
+   assert(is_in(obj), "only check if is in active generation for objects (" PTR_FORMAT ") in heap", p2i(obj));
+   assert(gen->is_old() || gen->is_young() || gen->is_global(),
+          "Active generation must be old, young, or global");
+ 
+   size_t index = heap_region_containing(obj)->index();
+ 
+   // No flickering!
+   assert(gen == active_generation(), "Race?");
+ 
+   switch (_affiliations[index]) {
+   case ShenandoahAffiliation::FREE:
+     // Free regions are in Old, Young, Global
+     return true;
+   case ShenandoahAffiliation::YOUNG_GENERATION:
+     // Young regions are in young_generation and global_generation, not in old_generation
+     return gen != (ShenandoahGeneration*)old_generation();
+   case ShenandoahAffiliation::OLD_GENERATION:
+     // Old regions are in old_generation and global_generation, not in young_generation
+     return gen != (ShenandoahGeneration*)young_generation();
+   default:
+     assert(false, "Bad affiliation (%d) for region " SIZE_FORMAT, _affiliations[index], index);
+     return false;
+   }
+ }
+ 
+ inline bool ShenandoahHeap::is_in_young(const void* p) const {
+   return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::YOUNG_GENERATION);
+ }
+ 
+ inline bool ShenandoahHeap::is_in_old(const void* p) const {
+   return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::OLD_GENERATION);
+ }
+ 
+ inline bool ShenandoahHeap::is_old(oop obj) const {
+   return active_generation()->is_young() && is_in_old(obj);
+ }
+ 
+ inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(const ShenandoahHeapRegion *r) {
+   return (ShenandoahAffiliation) _affiliations[r->index()];
+ }
+ 
+ inline void ShenandoahHeap::assert_lock_for_affiliation(ShenandoahAffiliation orig_affiliation,
+                                                         ShenandoahAffiliation new_affiliation) {
+   // A lock is required when changing from FREE to NON-FREE.  Though it may be possible to elide the lock when
+   // transitioning from in-use to FREE, the current implementation uses a lock for this transition.  A lock is
+   // not required to change from YOUNG to OLD (i.e. when promoting humongous region).
+   //
+   //         new_affiliation is:     FREE   YOUNG   OLD
+   //  orig_affiliation is:  FREE      X       L      L
+   //                       YOUNG      L       X
+   //                         OLD      L       X      X
+   //  X means state transition won't happen (so don't care)
+   //  L means lock should be held
+   //  Blank means no lock required because affiliation visibility will not be required until subsequent safepoint
+   //
+   // Note: during full GC, all transitions between states are possible.  During Full GC, we should be in a safepoint.
+ 
+   if ((orig_affiliation == ShenandoahAffiliation::FREE) || (new_affiliation == ShenandoahAffiliation::FREE)) {
+     shenandoah_assert_heaplocked_or_fullgc_safepoint();
+   }
+ }
+ 
+ inline void ShenandoahHeap::set_affiliation(ShenandoahHeapRegion* r, ShenandoahAffiliation new_affiliation) {
+ #ifdef ASSERT
+   assert_lock_for_affiliation(region_affiliation(r), new_affiliation);
+ #endif
+   _affiliations[r->index()] = (uint8_t) new_affiliation;
+ }
+ 
+ inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(size_t index) {
+   return (ShenandoahAffiliation) _affiliations[index];
+ }
+ 
  inline bool ShenandoahHeap::requires_marking(const void* entry) const {
    oop obj = cast_to_oop(entry);
    return !_marking_context->is_marked_strong(obj);
  }
  

@@ -300,10 +452,11 @@
  inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
    assert(collection_set() != nullptr, "Sanity");
    return collection_set()->is_in_loc(p);
  }
  
+ 
  inline bool ShenandoahHeap::is_stable() const {
    return _gc_state.is_clear();
  }
  
  inline bool ShenandoahHeap::is_idle() const {

@@ -312,10 +465,18 @@
  
  inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
    return _gc_state.is_set(MARKING);
  }
  
+ inline bool ShenandoahHeap::is_concurrent_young_mark_in_progress() const {
+   return _gc_state.is_set(YOUNG_MARKING);
+ }
+ 
+ inline bool ShenandoahHeap::is_concurrent_old_mark_in_progress() const {
+   return _gc_state.is_set(OLD_MARKING);
+ }
+ 
  inline bool ShenandoahHeap::is_evacuation_in_progress() const {
    return _gc_state.is_set(EVACUATION);
  }
  
  inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {

@@ -353,12 +514,11 @@
  
  template<class T>
  inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
    assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
  
-   ShenandoahMarkingContext* const ctx = complete_marking_context();
-   assert(ctx->is_complete(), "sanity");
+   ShenandoahMarkingContext* const ctx = marking_context();
  
    HeapWord* tams = ctx->top_at_mark_start(region);
  
    size_t skip_bitmap_delta = 1;
    HeapWord* start = region->bottom();

@@ -485,18 +645,10 @@
    } else {
      return nullptr;
    }
  }
  
- inline void ShenandoahHeap::mark_complete_marking_context() {
-   _marking_context->mark_complete();
- }
- 
- inline void ShenandoahHeap::mark_incomplete_marking_context() {
-   _marking_context->mark_incomplete();
- }
- 
  inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
    assert (_marking_context->is_complete()," sanity");
    return _marking_context;
  }
  
< prev index next >