RFR(s): 8252414: Redundant suspend check when determining if a java thread is safe
Robbin Ehn
robbin.ehn at oracle.com
Fri Aug 28 07:38:23 UTC 2020
Thanks Dan!
/Robbin
On 2020-08-28 01:14, Daniel D. Daugherty wrote:
> On 8/27/20 3:21 AM, Robbin Ehn wrote:
>> Hi all, please review.
>>
>> In 8221207 - "Redo JDK-8218446 - SuspendAtExit hangs" we fixed so a
>> thread is always blocked when suspended.
>>
>> And added this nice assert.
>> int JavaThread::java_suspend_self() {
>> assert(thread_state() == _thread_blocked, "wrong state for
>> java_suspend_self()");
>>
>> When checking if a thread is safepoint/handshake safe there no need to
>> look at ext suspend flag anymore, since the thread is blocked.
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8252414
>> Code:
>> http://cr.openjdk.java.net/~rehn/8252414/webrev/index.html
>
> Sorry for the delay. I had to go back and reread the
> "8221207: Redo JDK-8218446 - SuspendAtExit hangs" review thread.
>
>
> src/hotspot/share/runtime/handshake.cpp
> No comments.
>
> src/hotspot/share/runtime/safepoint.cpp
> No comments.
>
>> When checking if a thread is safepoint/handshake safe there no need to
>> look at ext suspend flag anymore, since the thread is blocked.
>
> I wouldn't quite phrase it that way. We consider a thread to
> be is_ext_suspended() when it's running native code also. In
> that case, it is _thread_in_native, but if it should happen
> to return from native then we'll catch it in
> JavaThread::java_suspend_self_with_safepoint_check() so it
> will become properly blocked.
>
> Thumbs up!
>
> Dan
>
>
>>
>> Passes t1-5
>>
>> Thanks, Robbin
>
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