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

[Denghui Dong]

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.

Thanks,
Denghui Dong

------------------------------------------------------------------
From:Erik Gahlin <erik.gahlin at oracle.com>
Send Time:2020年3月5日(星期四) 19:55
To:董登辉(卓昂) <denghui.ddh at alibaba-inc.com>
Cc:hotspot-jfr-dev <hotspot-jfr-dev at openjdk.java.net>; core-libs-dev <core-libs-dev at openjdk.java.net>; Alan Bateman <Alan.Bateman at oracle.com>
Subject:Re: RFR: 8238665: Add JFR event for direct memory statistics

We should avoid adding a dependency on java.management. The jdk.jfr module today only depends java.base so JFR can be used in constrained environments. All JMX related functionality is in jdk.management.jfr.

Erik

On 5 Mar 2020, at 10:54, Denghui Dong <denghui.ddh at alibaba-inc.com> wrote:
Hi Alan,

If I use ManagementFactoryHelper to get memory pools, I still need to modify src/java.management/share/classes/module-info.java
to export sun.management, right?

Thanks,
Denghui Dong
------------------------------------------------------------------
From:Alan Bateman <Alan.Bateman at oracle.com>
Send Time:2020年3月5日(星期四) 16:46
To:董登辉(卓昂) <denghui.ddh at alibaba-inc.com>; Erik Gahlin <erik.gahlin at oracle.com>; 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 02:44, Denghui Dong wrote:
> Hi Erik,
> Updated.
> Webrev: http://cr.openjdk.java.net/~ddong/8238665/webrev.01/
>
ManagementFactoryHelper has a method to get the list of MXBeans for the 
buffer pools. That could be easily changed to return an unmodifable 
list. That would allow you to emit statistics for memory-mapped files 
too (the current patch seems to be limited to emitting stats for direct 
buffers).

-Alan.