Proposal for back-porting JFR to OpenJDK8u

Andrey Petushkov andrey at
Wed Feb 20 13:35:57 UTC 2019

Dear Guangyu,

On 20 Feb 2019, at 15:44, guangyu.zhu <guangyu.zhu at<mailto:guangyu.zhu at>> wrote:

Hi Andrey,

I'm just coming back from the Spring Festival holiday and sorry for the late response. I am very happy that Azul has ported jfr to multiple platforms. Are there any further updates to your difference analysis?
Not yet, sorry. Was distracted to do some other stuff
I quickly studied the patch and found some differences:

- Your patch does not support thread sampling, and it looks like some code in jfrThreadSampler.cpp is commented out.
Absolutely. It's great you have implemented that in absence of threadSMR
- Your patch does not support the gc event on g1, Alibaba's patch supports g1 events, which you have already mentioned.
Not exactly. Azul code supports GC events for G1 however we miss some important information, like region types, heap occupancy etc
- Alibaba divides the test into two parts. The test relies on the hotspot whitebox being moved to the hotspot directory, while Azul saves all tests under jdk dircetory and adds the hotspot whitebox to the test library.
Right. I'm not sure what's the best way

I will spend more time comparing these two patches. Anyway, it seems that the jfr patch will enter jdk8u faster than we originally expected.
Well, at least some jdk8u incubator repos ;)



Sender:Andrey Petushkov <andrey at<mailto:andrey at>>
Sent At:2019 Feb. 16 (Sat.) 00:41
Recipient:Mario Torre <neugens at<mailto:neugens at>>; Andrew Haley <aph at<mailto:aph at>>; Severin Gehwolf <sgehwolf at<mailto:sgehwolf at>>; Mario Torre <neugens.limasoftware at<mailto:neugens.limasoftware at>>; jdk8u-dev <jdk8u-dev-bounces at<mailto:jdk8u-dev-bounces at>>; yumin qi <yumin.qi at<mailto:yumin.qi at>>; kingsum.chow <kingsum.chow at<mailto:kingsum.chow at>>; jdk8u-dev <jdk8u-dev at<mailto:jdk8u-dev at>>; denghui.ddh <denghui.ddh at<mailto:denghui.ddh at>>; guangyu.zhu <guangyu.zhu at<mailto:guangyu.zhu at>>
Subject:Re: Proposal for back-porting JFR to OpenJDK8u

[fixed subject, removed jfr-dev maillist]

In the meanwhile I’ve updated webrev with a backports of JDK-8207392 (JFR profiling for PPC) and shared part of (necessary for the latter) JDK-8159284


On 14 Feb 2019, at 14:20, Mario Torre <neugens at<mailto:neugens at>> wrote:

On Tue, Feb 12, 2019 at 12:41 PM Andrew Haley <aph at<mailto:aph at>> wrote:
On 2/11/19 1:01 PM, Mario Torre wrote:
> On Mon, Feb 11, 2019 at 12:29 PM Severin Gehwolf <sgehwolf at<mailto:sgehwolf at>> wrote:
>> On Fri, 2019-02-08 at 19:00 +0100, Mario Torre wrote:
>>> Andrew, do you think we can have a repository created for this
>>> purpose?
>> At the OpenJDK Committers Workshop a JDK 8u sandbox repository was
>> discussed. Perhaps that would fit the bill for this backport in a more
>> generic way?  "jfr-8u" branch in a jdk8u-dev/sandbox forest, perhaps?
> My understanding was that this was dismissed, but I'm happy either way.
> If we have an agreement on how to call the repository then Andrew will
> create one right away.
> Btw, I think the discussion should move to jdk8u-dev alone. I'm not
> sure if we will want to coordinate this effort on a separate mailing
> list though, what do you think?

I think it would be cleaner to have multiple repositories: having to deal
with branches make things pointlessly difficult. Maybe we should give this
some structure with subdirectories, so jdk8u/incubator/jfr. The advantage
of this is that a casual visitor is less likely to be confused.

I like this proposal, it is future proof as it would make it clear also if we ever had to add more of such repositories what they are for.


Mario Torre
Associate Manager, Software Engineering
Red Hat GmbH <<>>
9704 A60C B4BE A8B8 0F30  9205 5D7E 4952 3F65 7898

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