Dan,
Thank you a lot for reviewing this!
On 2/27/14 11:09 AM, Daniel D. Daugherty wrote:
On 2/27/14 1:25 AM, serguei.spit...@oracle.com wrote:
Please, review the fix for:
https://bugs.openjdk.java.net/browse/JDK-6471769
Open webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/hotspot/6471769-JVMTI-DEPTH.2
src/share/vm/runtime/vm_operations.hpp
No comments.
src/share/vm/prims/jvmtiEnvBase.hpp
No comments.
src/share/vm/prims/jvmtiEnv.cpp
No comments.
src/share/vm/prims/jvmtiEnvThreadState.cpp
No comments.
src/share/vm/prims/jvmtiEventController.cpp
JvmtiEventController::set_frame_pop() is called by
JvmtiEnvThreadState::set_frame_pop() which is called by
JvmtiEnv::NotifyFramePop().
The "MutexLocker mu(JvmtiThreadState_lock)" in
JvmtiEventController::set_frame_pop() protected the work
done by JvmtiEventControllerPrivate::set_frame_pop():
ets->get_frame_pops()->set(fpop);
recompute_thread_enabled(ets->get_thread()->jvmti_thread_state());
Your check is the right thing to do, thanks!
I had to explain this more clearly in this 2-nd review request.
The approach I've taken here is that all this code paths are executed
on the target thread or at a safepoint.
It is true for all 3 functions:
set_frame_pop(), clear_frame_pop() and clear_to_frame_pop().
And the updated assert guards ensure that it is the case.
It could be a good idea to add a No_Safepoint_Verifier for PopFrame()
and NotifyFramePop()
to make sure the current/target thread does not go to safepoint until it
is returned from
update_for_pop_top_frame() and set_frame_pop() correspondingly.
A No_Safepoint_Verifier can be also needed in the
JvmtiExport::post_method_exit().
These are all places where these functions are called:
prims/jvmtiEnv.cpp:
state->env_thread_state(this)->set_frame_pop(frame_number); //
JvmtiEnv::NotifyFramePop()
prims/jvmtiExport.cpp:
ets->clear_frame_pop(cur_frame_number); //
JvmtiExport::post_method_exit()
prims/jvmtiThreadState.cpp:
ets->clear_frame_pop(popframe_number); //
JvmtiThreadState::update_for_pop_top_frame()
The function JvmtiEnvThreadState::clear_to_frame_pop() is never called now.
Thanks,
Serguei
Since multiple threads can call JVM/TI NotifyFramePop() on the
same target thread, what keeps the threads from messing with
the list of frame pops simultaneously or messing with the
thread enabled events bits in parallel?
I suspect that this might also be an issue for
JvmtiEventController::clear_frame_pop() and
JvmtiEventController::clear_to_frame_pop() also.
src/share/vm/prims/jvmtiThreadState.cpp
No comments.
Dan
Summary:
It is the 2-nd round of review because the JTREG com/sun/jdi tests
discovered a regression
in the first round change. The issue was in the
JvmtiEventController::clear_frame_pop()
lock synchronization that is not allowed at safepoints.
As a result I've changed the JvmtiEnv::NotifyFramePop to use a VM
operation for safety.
Also, I've removed the lock synchronization from the 3 impacted
JvmtiEventController::
functions: set_frame_pop(), clear_frame_pop() and
clear_to_frame_pop().
Testing:
In progress: nsk.jvmti, nsk.jdi, nsk.jdwp, JTreg com/sun/jdi
Thanks,
Serguei
On 2/25/14 12:43 PM, serguei.spit...@oracle.com wrote:
Please, review the fix for:
https://bugs.openjdk.java.net/browse/JDK-6471769
Open webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/hotspot/6471769-JVMTI-DEPTH.1
Summary:
This is another Test Stabilization issue.
The fix is very similar to other JVMTI stabilization fixes.
It is to use safepoints for updating the PopFrame data instead of
relying on the
suspend equivalent condition mechanism
(JvmtiEnv::is_thread_fully_suspended())
which is not adequate from the reliability point of view.
Testing:
In progress: nsk.jvmti, nsk.jdi, nsk.jdwp, JTreg com/sun/jdi
Thanks,
Serguei
