RFR: 8351925: JFR: Microsecond time format precision for JFR tool

[Aleksey Shipilev]

On Fri, 14 Mar 2025 16:17:13 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

> The default mode (PrettyWriter) aims to present human-readable output, striking a balance between clarity and concision. For more detailed information, including timestamps and time spans with nine-digit precision, `jfr print --json` is available as an alternative.

I understand, no pressure.

I do see folks in my vicinity (myself included) reaching for human-readable output for quick and dirty analysis. Very often that human-readable output is really great to quickly capture what is going on. At the scales we operate on, it is useful to see microseconds to correlate events happening within a millisecond. Switching to JSON does work, but it feels like an unnecessary friction.

Microsecond precision for timings is not uncommon. For example, Linux perf tools routinely report ISO 8601 timestamps with microsecond precision.

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PR Comment: https://git.openjdk.org/jdk/pull/24029#issuecomment-2754890252