RFR: 8351594: JFR: Rate-limited sampling of Java events [v6]

[Andrey Turbanov]

On Thu, 5 Jun 2025 08:40:44 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> Could I have review of an enhancement that adds rate-limited sampling to Java events, including five events in the JDK (SocketRead, SocketWrite, FileRead, FileWrite, and JavaExceptionThrow).
>> 
>> Testing: test/jdk/jdk/jfr
>> 
>> Thanks
>> Erik
>
> Erik Gahlin 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 nine additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'upstream/master' into throttle-mania-3
>  - Merge remote-tracking branch 'upstream/master' into throttle-mania-3
>  - Merge remote-tracking branch 'upstream/master' into throttle-mania-3
>  - Fix adjust boundary
>  - Some reviewer feedback
>  - Consistent annotation
>  - Fix typos
>  - Fix whitespace
>  - Initial

src/java.base/share/classes/java/io/RandomAccessFile.java line 594:

> 592:         } finally {
> 593:             long end = FileWriteEvent.timestamp();
> 594:             long duration =  end - start;

Suggestion:

            long duration = end - start;

src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java line 65:

> 63: public final class EventInstrumentation {
> 64:     public static final long MASK_THROTTLE              = 1 << 62;
> 65:     public static final long MASK_THROTTLE_CHECK        = 1 << 63;

Let's align
Suggestion:

    public static final long MASK_THROTTLE               = 1 << 62;
    public static final long MASK_THROTTLE_CHECK         = 1 << 63;

src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java line 593:

> 591:         if (throttled) {
> 592:             codeBuilder.aload(0);
> 593:             getfield(codeBuilder, eventClassDesc,  ImplicitFields.FIELD_DURATION);

Suggestion:

            getfield(codeBuilder, eventClassDesc, ImplicitFields.FIELD_DURATION);

test/jdk/jdk/jfr/api/recording/settings/TestSettingsAvailability.java line 93:

> 91:         testSetting(EventNames.JVMInformation, "enabled", "period");
> 92:         testSetting(EventNames.FileRead, "enabled", "threshold", "stackTrace", "throttle");
> 93:         testSetting(EventNames.FileWrite, "enabled", "threshold","stackTrace", "throttle");

Suggestion:

        testSetting(EventNames.FileWrite, "enabled", "threshold", "stackTrace", "throttle");

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25559#discussion_r2128322876
PR Review Comment: https://git.openjdk.org/jdk/pull/25559#discussion_r2128321445
PR Review Comment: https://git.openjdk.org/jdk/pull/25559#discussion_r2128322474
PR Review Comment: https://git.openjdk.org/jdk/pull/25559#discussion_r2128323708