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8010196: NPG: Internal Error: Metaspace allocation lock -- possible deadlock

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Refactor the CLD dependency list into a separate class. Use an ObjectLocker to synchronize additions to the CLD dependency list.

Reviewed-by: stefank, coleenp
This commit is contained in:
Mikael Gerdin 2013-04-10 13:27:35 +02:00
parent 6f3fdce7b3
commit 0edccc9e61
3 changed files with 159 additions and 17 deletions
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29
hotspot/src/share/vm/classfile/classLoaderData.cpp
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@ -70,15 +70,19 @@ ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) :
_is_anonymous(is_anonymous), _keep_alive(is_anonymous), // initially
_metaspace(NULL), _unloading(false), _klasses(NULL),
_claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
_next(NULL), _dependencies(NULL),
_next(NULL), _dependencies(),
_metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
// empty
}
void ClassLoaderData::init_dependencies(TRAPS) {
_dependencies.init(CHECK);
}
void ClassLoaderData::Dependencies::init(TRAPS) {
// Create empty dependencies array to add to. CMS requires this to be
// an oop so that it can track additions via card marks. We think.
_dependencies = (oop)oopFactory::new_objectArray(2, CHECK);
_list_head = oopFactory::new_objectArray(2, CHECK);
}
bool ClassLoaderData::claim() {
@ -95,13 +99,17 @@ void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool m
}
f->do_oop(&_class_loader);
f->do_oop(&_dependencies);
_dependencies.oops_do(f);
_handles->oops_do(f);
if (klass_closure != NULL) {
classes_do(klass_closure);
}
}
void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
f->do_oop((oop*)&_list_head);
}
void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
klass_closure->do_klass(k);
@ -154,14 +162,14 @@ void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
// It's a dependency we won't find through GC, add it. This is relatively rare
// Must handle over GC point.
Handle dependency(THREAD, to);
from_cld->add_dependency(dependency, CHECK);
from_cld->_dependencies.add(dependency, CHECK);
}
void ClassLoaderData::add_dependency(Handle dependency, TRAPS) {
void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
// Check first if this dependency is already in the list.
// Save a pointer to the last to add to under the lock.
objArrayOop ok = (objArrayOop)_dependencies;
objArrayOop ok = _list_head;
objArrayOop last = NULL;
while (ok != NULL) {
last = ok;
@ -184,16 +192,17 @@ void ClassLoaderData::add_dependency(Handle dependency, TRAPS) {
objArrayHandle new_dependency(THREAD, deps);
// Add the dependency under lock
locked_add_dependency(last_handle, new_dependency);
locked_add(last_handle, new_dependency, THREAD);
}
void ClassLoaderData::locked_add_dependency(objArrayHandle last_handle,
objArrayHandle new_dependency) {
void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
objArrayHandle new_dependency,
Thread* THREAD) {
// Have to lock and put the new dependency on the end of the dependency
// array so the card mark for CMS sees that this dependency is new.
// Can probably do this lock free with some effort.
MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
oop loader_or_mirror = new_dependency->obj_at(0);