Shenandoah Events

[zgu at redhat.com]

On Fri, 2019-01-11 at 15:20 -0500, Ken Dobson wrote:
> Hi, 
> 
> Actually it shouldn't be in the default jfc file, you are able to
> configure the events yourself by enabling them before you begin a
> recording. You wouldn't want these events enabled by default, they
> should be enabled explicitly by those who would like to use them.
> 
> That being said I have been unable to get the events to show up in
> the event browser. Using the jfr command from the CLI it appears the
> events are being emitted correctly so it seems it's an issue on the
> JMC side that I am currently attempting to solve.
> 
Yes, you can enable the events at the point of recording from JMC, and
seems that events are emitted.

jfr summary ...

 Event Type                              Count  Size (bytes) 
=============================================================
 jdk.ShenandoahHeapRegionStateChange   3843823      94125936
 jdk.ShenandoahHeapRegionInformation     63072       1332094

I need to look into state change events, seems excessive ...

Thanks,

-Zhengyu


> Ken
> 
> On Fri, Jan 11, 2019 at 1:16 PM Jie Kang <jkang at redhat.com> wrote:
> > 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/w
> > ebrev.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/sh
> > are/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
> > > > > >