The JavaThread flag hide_from_external_view is set for various threads including compiler threads. The intent is to hide threads with this flag from external view. However, it seems the JVMTI events can be posted on behalf of such threads. At least, I do not see any mechanism that prevents this to happen. We need to make the threads hiding mechanism to be consistent.
It is not clear if it is possible to skip all JVMTI events for threads with the flag hide_from_external_view. For instance, the ServiceThread has such flag but it is used to post deferred events originated by compiler threads. All JVMTI events hiding mechanisms have to be balanced properly and designed together.