RFR: 8266723: JFR periodic events are causing extra allocations

[Jaroslav Bachorík]

Gentle ping?

-JB-

On Fri, May 7, 2021 at 5:54 PM Jaroslav Bachorík
<jaroslav.bachorik at datadoghq.com> wrote:
>
> Please, review the following fix.
>
> JIRA:  https://bugs.openjdk.java.net/browse/JDK-8266723
> Webrev:
>  - hotspot: http://cr.openjdk.java.net/~jbachorik/8266723/hotspot/00/webrev/
>  - jdk: http://cr.openjdk.java.net/~jbachorik/8266723/jdk/00/webrev/
>
> In short, the JFR backport for JDK 8 could not bring in the whole JVM
> logging framework and took a several shortcuts. Unfortunately, one of
> the shortcuts is causing the log messages always generated but not
> persisted resulting in possible disturbance in GC due to excessive
> allocations.
>
> The gist of the patch is binding the java side JFR logger log level
> check with the global 'LogJFR' flag which is already used in the
> native JFR logger implementation.
>
> The path builds fine and passes tier1 and jfr tests on linux. Since
> the changes are not platform specific I am expecting the tests passing
> on other platforms as well.
> If there is a volunteer able to run tests for this patch on more
> platforms it would be welcome.
>
> Cheers,
>
> -JB-