[11u] RFR: 8209061 & 8209062: G1MonitoringSupport changes

[Vladimir Kempik]

Hello Langer

>Another thing: Looking at JBS I can see that JDK-8208498 was marked as a blocker for JDK-8209061 and the former hasn't been backported to 11. Is that an issue
>Generally, would it be possible to fix the issue of JDK-8207200 in a way that's less invasive?

well, I have tried to make 8207200 less invasive by not including 8208498.

There is a race condition in g1 monitoring which still can be see by some openjdk11 users ( commited < used) and this is the attempt to fix it.
I have verified it helps at least one user. Sadly I don’t have a reproducer.

Regards, Vladimir


> 17 сент. 2020 г., в 10:43, Langer, Christoph <christoph.langer at sap.com> написал(а):
> 
> Hi,
> 
> I've just looked at approving this series of backports (JDK-8209061, JDK-8209062 and JDK-8207200).
> 
> While I'm sure that JDK-8207200 fixes an important issue and I also trust your reviews of the backports, I can see that these 3 patches together mean some significant changes in the area of G1 GC. This makes me kind of hesitant to approve the backports right away. I'd like to get some assessment/reassurance of the other JDK11 maintainers (aph, sgehwolf) on whether we should admit them or not?
> 
> Also, Aleksey, maybe you can give some technical advice as a gc expert if you think these backports are feasible?
> 
> Another thing: Looking at JBS I can see that JDK-8208498 was marked as a blocker for JDK-8209061 and the former hasn't been backported to 11. Is that an issue?
> 
> Generally, would it be possible to fix the issue of JDK-8207200 in a way that's less invasive?
> 
> Please understand that I'd like to err on the side of caution here...
> 
> Thanks & Best regards
> Christoph
> 
>> -----Original Message-----
>> From: jdk-updates-dev <jdk-updates-dev-retn at openjdk.java.net> On
>> Behalf Of John Cuthbertson
>> Sent: Dienstag, 15. September 2020 19:07
>> To: Vladimir Kempik <vkempik at azul.com>
>> Cc: jdk-updates-dev at openjdk.java.net
>> Subject: Re: [11u] RFR: 8209061 & 8209062: G1MonitoringSupport changes
>> 
>> Hi Vladimir,
>> 
>> On Sep 3, 2020, at 5:28 AM, Vladimir Kempik
>> <vkempik at azul.com<mailto:vkempik at azul.com>> wrote:
>> 
>> Hello
>> 
>> Please review these backports of JDK-8209061:Move G1 serviceability
>> functionality to G1MonitoringSupport  and JDK-8209062:Clean up
>> G1MonitoringSupport to jdk11u
>> 
>> These backports are prerequestes for JDK-8207200 which we can see in the
>> wild with jdk8 and jdk11.
>> 
>> JDK-8209061 and JDK-8209062 applies mostly clean, very few places where it
>> wasn’t clean due to surrounding code or code layout.
>> 
>> after these two, JDK-8207200 applies cleanly.
>> 
>> Testing: tier1.
>> 
>> The webrevs:
>> 
>> http://cr.openjdk.java.net/~vkempik/8209061/webrev.00/
>> 
>> This looks good to me and matches
>> http://hg.openjdk.java.net/jdk/jdk/rev/ec014e5694ec.
>> 
>> http://cr.openjdk.java.net/~vkempik/8209062/webrev.00/
>> 
>> This looks good to me also and matches
>> http://hg.openjdk.java.net/jdk/jdk/rev/9a5200b84046.
>> 
>> 
>> All mentioned bugs:
>> https://bugs.openjdk.java.net/browse/JDK-8209062
>> https://bugs.openjdk.java.net/browse/JDK-8209061
>> https://bugs.openjdk.java.net/browse/JDK-8207200
>> 
>> Original changesets:
>> 8209061: http://hg.openjdk.java.net/jdk/jdk/rev/ec014e5694ec
>> 8209062: http://hg.openjdk.java.net/jdk/jdk/rev/9a5200b84046
>> 
>> Thanks, Vladimir
>> 
>> Regards,
>> 
>> JohnC