Re: RFR: 8238665: Add JFR event for direct memory statistics

[Denghui Dong]

Ping.
Could you review this?

Thanks,
Denghui Dong
------------------------------------------------------------------
From:董登辉(卓昂) <denghui.ddh at alibaba-inc.com>
Send Time:2020年3月8日(星期日) 23:42
To:Erik Gahlin <erik.gahlin at oracle.com>; Alan Bateman <Alan.Bateman at oracle.com>
Cc:hotspot-jfr-dev <hotspot-jfr-dev at openjdk.java.net>; core-libs-dev <core-libs-dev at openjdk.java.net>
Subject:Re: RFR: 8238665: Add JFR event for direct memory statistics

Hi Alan and Erik,

Thanks for the review.

Webrev has been updated in http://cr.openjdk.java.net/~ddong/8238665/webrev.02/

Testing: jdk/jfr, java/lang/management/ all passed

Summary: add a method in jdk.internal.misc.VM to get an unmodifiable buffer pool list.

Cheers,
Denghui Dong

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From:Alan Bateman <Alan.Bateman at oracle.com>
Send Time:2020年3月8日(星期日) 22:13
To:董登辉(卓昂) <denghui.ddh at alibaba-inc.com>; Erik Gahlin <erik.gahlin at oracle.com>
Cc:hotspot-jfr-dev <hotspot-jfr-dev at openjdk.java.net>; core-libs-dev <core-libs-dev at openjdk.java.net>
Subject:Re: RFR: 8238665: Add JFR event for direct memory statistics

 On 05/03/2020 15:19, Denghui Dong wrote:
Hi Alan and Erik,

 Sorry, I'm not sure if I fully understand what you mean.
 For this feature, I still think exporting jdk.internal.access to jdk.jfr is a good solutionsince there are
 some other packages has already exported to jdk.jfr in this module.
 I think it would be cleaner to put a helper in jdk.internal.misc so that JFR has access to the counters for each of the buffer pools. That would avoid additional plumbing when you extend it to mapped buffers. As I mentioned in one of the other mails, ManagementFactoryHelper.getBufferPoolMXBeans() could be changed to use it too. From the perspective of java.base then it's a lot nicer as anyone touching the buffer code doesn't need to have to concerned with direct access from code in java.management and jdk.jfr.

 -Alan