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8162553: Crash in class unloading due to null CLD having a zero _keep_alive value

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Correct the refcounting of ClassLoaderData::_keep_alive for anonymous classes.

Reviewed-by: acorn, coleenp, dholmes, jiangli
This commit is contained in:
Lois Foltan 2016-08-11 11:41:11 -04:00
parent 942ee05da5
commit 2579620b6d
2 changed files with 13 additions and 7 deletions
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12
hotspot/src/share/vm/classfile/classLoaderData.cpp
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@ -126,13 +126,17 @@ bool ClassLoaderData::claim() {
// ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
// it is being defined, therefore _keep_alive is not volatile or atomic.
void ClassLoaderData::inc_keep_alive() {
assert(_keep_alive >= 0, "Invalid keep alive count");
_keep_alive++;
if (is_anonymous()) {
assert(_keep_alive >= 0, "Invalid keep alive increment count");
_keep_alive++;
}
}
void ClassLoaderData::dec_keep_alive() {
assert(_keep_alive > 0, "Invalid keep alive count");
_keep_alive--;
if (is_anonymous()) {
assert(_keep_alive > 0, "Invalid keep alive decrement count");
_keep_alive--;
}
}
void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {

8
hotspot/src/share/vm/classfile/classLoaderData.hpp
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@ -176,9 +176,9 @@ class ClassLoaderData : public CHeapObj<mtClass> {
Mutex* _metaspace_lock; // Locks the metaspace for allocations and setup.
bool _unloading; // true if this class loader goes away
bool _is_anonymous; // if this CLD is for an anonymous class
int _keep_alive; // if this CLD is kept alive without a keep_alive_object().
// Currently used solely for anonymous classes.
// _keep_alive does not need to be volatile or
s2 _keep_alive; // if this CLD is kept alive without a keep_alive_object().
// Used for anonymous classes and the boot class
// loader. _keep_alive does not need to be volatile or
// atomic since there is one unique CLD per anonymous class.
volatile int _claimed; // true if claimed, for example during GC traces.
// To avoid applying oop closure more than once.
@ -289,6 +289,8 @@ class ClassLoaderData : public CHeapObj<mtClass> {
return _unloading;
}
// Used to refcount an anonymous class's CLD in order to
// indicate their aliveness without a keep_alive_object().
void inc_keep_alive();
void dec_keep_alive();