Shenandoah Events

[Jie Kang]

On Fri, Jan 11, 2019 at 1:02 PM Jie Kang <jkang at redhat.com> wrote:
>
> On Fri, Jan 11, 2019 at 8:40 AM <zgu at redhat.com> wrote:
> >
> > Hi Guys,
> >
> > Here is my initial implementation of Shenandoah heap layout JFR events:
> >
> > http://cr.openjdk.java.net/~zgu/shenandoah/jfr_sh_heap_layout/webrev.00
> > /
> >
> > The patch is good for jdk/jdk and shenandoah/jdk repos. I have no idea
> > how to test it without JMC counterpart. If you have any suggestions,
> > please let me know.

Hi,

Also, the default jfc file (java flight recording configuration) does
not have the Shenandoah events enabled so they won't be fired unless
you supply a custom jfc, or maybe patch the repo to produce a
default.jfc that does have them enabled. It looks like ZGC related
events are there so it should be fine to add Shenandoah ones as well.

The jfc files in jdk/jdk are default.jfc and profile.jfc @
http://hg.openjdk.java.net/jdk/jdk/file/fbc921683f02/src/jdk.jfr/share/conf/jfr

Assuming the events work, they will be seen then.


Regards,

>
> Hi,
>
> For testing without JMC, you can add options to the JVM to create a
> flight recording and then use the CLI tool 'jfr' that is part of
> OpenJDK to examine the jfr file for the existence of Shenandoah
> events.
>
> Some hopefully helpful terminal output from a build of jdk/jdk:
>
> [jkang at unused-10-15-17-52 linux-x86_64-server-release]$ jdk/bin/jfr
> Tool for working with Flight Recorder files (.jfr)
>
> Before using this tool, you must have a recording file.
> A file can be created by starting a recording from command line:
>
>  java -XX:StartFlightRecording:filename=recording.jfr,duration=30s ...
>
> A recording can also be started on already running Java Virtual Machine:
>
>  jcmd (to list available pids)
>  jcmd <pid> JFR.start
>
> Recording data can be dumped to file using the JFR.dump command:
>
>  jcmd <pid> JFR.dump filename=recording.jfr
>
> The contents of the recording can then be printed, for example:
>
>  jfr print recording.jfr
>
>  jfr print --events CPULoad,GarbageCollection recording.jfr
>
>  jfr print --json --events CPULoad recording.jfr
>
>  jfr print --categories "GC,JVM,Java*" recording.jfr
>
>  jfr print --events "jdk.*" --stack-depth 64 recording.jfr
>
>  jfr summary recording.jfr
>
>  jfr metadata recording.jfr
>
> For more information about available commands, use 'jfr help'
>
>
> Regards,
>
> >
> > Hopefully, it is enough for you to get things started.
> >
> > Thanks,
> >
> > -Zhengyu
> >
> > > On Wed, 2019-01-09 at 18:14 +0100, Mario Torre wrote:
> > > > Hello all!
> > > >
> > > > I would like to have a quick meeting to discuss the JFR events in
> > > > shenandoah, when would be a good time?
> > > >
> > > > I have a slot tomorrow at 3 PM (9AM your time I believe), would
> > > > that
> > > > work for you?
> > > >
> > > > Cheers,
> > > > Mario
> > > >