RFR: 8203359: Container level resources events [v10]

[Erik Gahlin]

On Thu, 22 Apr 2021 16:00:32 GMT, Jaroslav Bachorik <jbachorik at openjdk.org> wrote:

>> With this change it becomes possible to surface various cgroup level metrics (available via `jdk.internal.platform.Metrics`) as JFR events.
>> 
>> Only a subset of the metrics exposed by `jdk.internal.platform.Metrics` is turned into JFR events to start with.
>> * CPU related metrics
>> * Memory related metrics
>> * I/O related metrics
>> 
>> For each of those subsystems a configuration data will be emitted as well. The initial proposal is to emit the configuration data events at least once per chunk and the metrics values at 30 seconds interval. 
>> By using these values the emitted events seem to contain useful information without increasing overhead (the metrics values are read from `/proc` filesystem so that should not be done too frequently).
>
> Jaroslav Bachorik has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 13 additional commits since the last revision:
> 
>  - Prevent event container bytecode generation if no container present
>  - Fix event metadata
>  - Roll back conditional registration of container events
>  - Remove container events flag
>  - Remove trailing spaces
>  - Doh
>  - Report container type and register events conditionally
>  - Remove unused test files
>  - Initial test support for JFR container events
>  - Update the JFR control files
>  - ... and 3 more: https://git.openjdk.java.net/jdk/compare/904d9495...04c3f092

src/jdk.jfr/share/classes/jdk/jfr/internal/Utils.java line 729:

> 727: 
> 728:     public static boolean shouldSkipBytecode(String eventName, Class<?> superClass) {
> 729:         if (!superClass.getName().equals("jdk.jfr.events.AbstractJDKEvent")) {

Was there a problem checking against the class instance? If so, perhaps you could add a check that the class is in the boot class loader (null).

src/jdk.jfr/share/classes/jdk/jfr/internal/Utils.java line 737:

> 735:     private static Metrics getMetrics() {
> 736:         if (metrics == null) {
> 737:             metrics = Metrics.systemMetrics();

Will this not lead to a lookup every time in an non-container environment?

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PR: https://git.openjdk.java.net/jdk/pull/3126