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8003420: NPG: make new GC root for pd_set

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Move protection domain oops from system dictionary entries into a seperate set; the system dictionary references entries in that set now. This allows fast iteration during non-classunloading garbage collection. Implementation based on initial prototype from Ioi Lam (iklam).

Reviewed-by: coleenp, iklam
This commit is contained in:
Thomas Schatzl 2013-10-09 10:57:01 +02:00
parent 2d75de8b05
commit 30ed89669a
7 changed files with 403 additions and 40 deletions
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28
hotspot/src/share/vm/classfile/systemDictionary.cpp
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@ -1697,6 +1697,24 @@ int SystemDictionary::calculate_systemdictionary_size(int classcount) {
return newsize;
}
#ifdef ASSERT
class VerifySDReachableAndLiveClosure : public OopClosure {
private:
BoolObjectClosure* _is_alive;
template <class T> void do_oop_work(T* p) {
oop obj = oopDesc::load_decode_heap_oop(p);
guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
}
public:
VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
virtual void do_oop(oop* p) { do_oop_work(p); }
virtual void do_oop(narrowOop* p) { do_oop_work(p); }
};
#endif
// Assumes classes in the SystemDictionary are only unloaded at a safepoint
// Note: anonymous classes are not in the SD.
bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
@ -1707,7 +1725,15 @@ bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
unloading_occurred = dictionary()->do_unloading();
constraints()->purge_loader_constraints();
resolution_errors()->purge_resolution_errors();
}
}
// Oops referenced by the system dictionary may get unreachable independently
// of the class loader (eg. cached protection domain oops). So we need to
// explicitly unlink them here instead of in Dictionary::do_unloading.
dictionary()->unlink(is_alive);
#ifdef ASSERT
VerifySDReachableAndLiveClosure cl(is_alive);
dictionary()->oops_do(&cl);
#endif
return unloading_occurred;
}