RFR: 8258408: SystemDictionary passes TRAPS to functions that don't throw exceptions [v2]

[David Holmes]

On Fri, 18 Dec 2020 02:14:44 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> // definer must notify any waiting threads
>>   {
>>     MutexLocker mu(THREAD, SystemDictionary_lock);
>>     PlaceholderEntry* probe = placeholders()->get_entry(name_hash, name_h, loader_data);
>>     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
>>     if (!HAS_PENDING_EXCEPTION) {
>>       probe->set_instance_klass(k);
>>     }
>>     probe->set_definer(NULL);
>>     placeholders()->find_and_remove(name_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
>>     SystemDictionary_lock->notify_all();
>>   }
>
> old code vs. new code.

Right so my point is that in the new code:

probe->set_definer(NULL);
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();

you can now call these while an exception is pending. Whether that is harmless or not depends on the details of that code. I poked around a little and it seems okay but it isn't at all obvious that it is okay.

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PR: https://git.openjdk.java.net/jdk/pull/1808