git: openjdk/jdk: 8261034: improve jcmd GC.class_histogram to support parallel

[Hamlin Li]

Changeset: 3c47cab6
Author:    Hamlin Li <mli at openjdk.org>
Date:      2021-05-12 01:06:44 +0000
URL:       https://git.openjdk.java.net/jdk/commit/3c47cab6db949b19cfd300139cbdbf81fb521e68

8261034: improve jcmd GC.class_histogram to support parallel

Reviewed-by: cjplummer, sspitsyn

! src/hotspot/share/services/diagnosticCommand.cpp
! src/hotspot/share/services/diagnosticCommand.hpp
- test/hotspot/jtreg/serviceability/dcmd/gc/ClassHistogramAllTest.java
! test/hotspot/jtreg/serviceability/dcmd/gc/ClassHistogramTest.java