On Sat, 25 Jun 2022 01:35:38 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
>> src/hotspot/share/prims/jvmtiExport.cpp line 1702:
>>
>>> 1700: } else {
>>> 1701: post_object_free_on_java_thread(env, objects);
>>> 1702: }
>>
>> Can you explain why sometimes it is a VMThread and why sometimes it is a
>> JavaThread?
>
> I hope, it is okay if I explain it. :)
> The `post_object_free` can be called in different contexts.
> It is (recursively) called from `JvmtiTagMap::check_hashmaps_for_heapwalk()`
> which is used in VM_ops:
> - VM_HeapIterateOperation
> - VM_HeapWalkOperation
>
> Also, the `post_object_free` is called from `JvmtiTagMap` functions:
> - flush_object_free_events
> - get_objects_with_tags
> which can be called from the `ServiceThread` or the JVMTI functions like
> `SetEvenNotificationMode`, `SetEventCallBacks` or `GetObjectsWithTags`.
@sspitsyn Thanks.
Yes, `JvmtiTagMap::check_hashmaps_for_heapwalk()` is where I saw the call from
`VMThread`.
This patch is intended to **not** post `ObjectFree` events on `VMThread`, so I
am going to move this PR back to draft state and take another look.
-------------
PR: https://git.openjdk.org/jdk/pull/9168
