On Tue, 29 Apr 2025 09:48:05 GMT, Casper Norrbin <cnorr...@openjdk.org> wrote:
>> Hi everyone, >> >> This change removes the legacy `PerfData` sampling mechanism implemented >> through the `StatSampler` — an always-on periodic task that runs every 50ms >> my default. The sampling feature was originally introduced to collect >> performance counters and timestamps, but has since seen very little use. >> >> For G1/ZGC, the only sampled value is a timestamp (`sun.os.hrt.ticks`). For >> Serial/Parallel, it also samples some heap space counters, but these are >> already updated after each GC cycle, making the sampling redundant. With >> sampling removed, the `PerfDataSamplingInterval` flag becomes obsoleted, as >> it no longer serves any purpose. >> >> The only thing relying on the sampled timestamps is `jstat`: running `jstat >> -t` prints an extra column with the time since VM start. To preserve this >> funcitonality, we can calculate the timestamps as an offset from the already >> existing `sun.rt.createVmBeginTime` instead. > > Casper Norrbin has updated the pull request incrementally with one additional > commit since the last revision: > > feedback fixes Reviewed only `hotspot` changes. Not familiar with other parts. ------------- Marked as reviewed by ayang (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/24872#pullrequestreview-2802821239
