On Fri, 25 Apr 2025 10:38:39 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. This pull request has now been integrated. Changeset: 6ebae6cd Author: Casper Norrbin <cnorr...@openjdk.org> Committer: Albert Mingkun Yang <ay...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/6ebae6cded49f9b0b0d42899af3303647eca7848 Stats: 864 lines in 25 files changed: 150 ins; 655 del; 59 mod 8241678: Remove PerfData sampling via StatSampler Reviewed-by: jsjolen, ayang ------------- PR: https://git.openjdk.org/jdk/pull/24872
