As we discussed verbally, I suggest adding a line like this at the beginning of
every low-level MemberNameTable access function:
assert_locked_or_safepoint(MemberNameTable_lock);
(I'm modeling this from SystemDictionary::find_class and its brothers.)
The rest of it looks good. Reviewed!
— John
On Apr 15, 2013, at 10:59 AM, serguei.spit...@oracle.com wrote:
>>
>> b) do we need to use the MemberNameTable_lock to guard this?
>
> I don't think so.
> This deallocation must be done at a safepoint.
> We can't grab locks at safepoints.
>
> These are the details:
>
> classLoaderData.cpp:
>
> // Deallocate free metadata on the free list. How useful the PermGen was!
> void ClassLoaderData::free_deallocate_list() {
> // Don't need lock, at safepoint
> assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
> . . .
> } else if (m->is_klass()) {
> MetadataFactory::free_metadata(this, (InstanceKlass*)m);
> . . .
> }
>
> metadataFactory.hpp:
>
> // Deallocation method for metadata
> template <class T>
> static void free_metadata(ClassLoaderData* loader_data, T md) {
> if (md != NULL) {
> . . .
> md->deallocate_contents(loader_data);
> loader_data->metaspace_non_null()->deallocate((MetaWord*)md, size,
> md->is_klass());
> }
> }
>
> instanceKlass.cpp:
>
> void InstanceKlass::deallocate_contents(ClassLoaderData* loader_data) {
> . . .
> release_C_heap_structures();
> . . .
> }
