// Move class loader data from main list to the unloaded list for unloading
// and deallocation later.
bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
bool clean_previous_versions) {
ClassLoaderData* data = _head;
ClassLoaderData* prev = NULL;
bool seen_dead_loader = false;
// Mark metadata seen on the stack only so we can delete unneeded entries.
// Only walk all metadata, including the expensive code cache walk, for Full GC
// and only if class redefinition and if there's previous versions of
// Klasses to delete.
bool walk_all_metadata = clean_previous_versions &&
JvmtiExport::has_redefined_a_class() &&
InstanceKlass::has_previous_versions();
MetadataOnStackMark md_on_stack(walk_all_metadata);
// Save previous _unloading pointer for CMS which may add to unloading list before
// purging and we don't want to rewalk the previously unloaded class loader data.
_saved_unloading = _unloading;
data = _head;
while (data != NULL) {
if (data->is_alive(is_alive_closure)) {
// clean metaspace
if (walk_all_metadata) {
data->classes_do(InstanceKlass::purge_previous_versions);
}
data->free_deallocate_list();
prev = data;
data = data->next();
continue;
}
seen_dead_loader = true;
ClassLoaderData* dead = data;
dead->unload();
data = data->next();
// Remove from loader list.
// This class loader data will no longer be found
// in the ClassLoaderDataGraph.
if (prev != NULL) {
prev->set_next(data);
} else {
assert(dead == _head, "sanity check");
_head = data;
}
dead->set_next(_unloading);
_unloading = dead;
}
if (seen_dead_loader) {
post_class_unload_events();
}
return seen_dead_loader;
}
// Move class loader data from main list to the unloaded list for unloading
// and deallocation later.
bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) {
ClassLoaderData* data = _head;
ClassLoaderData* prev = NULL;
bool seen_dead_loader = false;
// Save previous _unloading pointer for CMS which may add to unloading list before
// purging and we don't want to rewalk the previously unloaded class loader data.
_saved_unloading = _unloading;
// mark metadata seen on the stack and code cache so we can delete
// unneeded entries.
bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
MetadataOnStackMark md_on_stack;
while (data != NULL) {
if (data->is_alive(is_alive_closure)) {
if (has_redefined_a_class) {
data->classes_do(InstanceKlass::purge_previous_versions);
}
data->free_deallocate_list();
prev = data;
data = data->next();
continue;
}
seen_dead_loader = true;
ClassLoaderData* dead = data;
dead->unload();
data = data->next();
// Remove from loader list.
// This class loader data will no longer be found
// in the ClassLoaderDataGraph.
if (prev != NULL) {
prev->set_next(data);
} else {
assert(dead == _head, "sanity check");
_head = data;
}
dead->set_next(_unloading);
_unloading = dead;
}
if (seen_dead_loader) {
post_class_unload_events();
}
return seen_dead_loader;
}
// Add a new class loader data node to the list. Assign the newly created
// ClassLoaderData into the java/lang/ClassLoader object as a hidden field
ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
// We need to allocate all the oops for the ClassLoaderData before allocating the
// actual ClassLoaderData object.
ClassLoaderData::Dependencies dependencies(CHECK_NULL);
No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
// ClassLoaderData in the graph since the CLD
// contains unhandled oops
ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
if (!is_anonymous) {
ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
// First, Atomically set it
ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
if (old != NULL) {
delete cld;
// Returns the data.
return old;
}
}
// We won the race, and therefore the task of adding the data to the list of
// class loader data
ClassLoaderData** list_head = &_head;
ClassLoaderData* next = _head;
do {
cld->set_next(next);
ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
if (exchanged == next) {
if (TraceClassLoaderData) {
ResourceMark rm;
tty->print("[ClassLoaderData: ");
tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
cld->loader_name());
tty->print_cr("]");
}
return cld;
}
next = exchanged;
} while (true);
}
