RFR: 8273217: Make ParHeapInspectTask _safepoint_check_never

[David Holmes]

On Wed, 1 Sep 2021 01:40:17 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Make lock be declared as safepoint_check_never.
> Ran tier1-3 tests and test that uses this code: serviceability/dcmd/gc/ClassHistogramTest.java

Hi Coleen,

The main change is fine, but the other seems unnecessary - see comment below.

Thanks,
David

src/hotspot/share/memory/heapInspection.cpp line 564:

> 562:   missed_count = ric.missed_count();
> 563:   {
> 564:     MutexLocker x(&_mutex, Mutex::_no_safepoint_check_flag);

This change seems unnecessary - this lock is only taken by GC threads, or the VMThread (?), never a JavaThread, but this change makes it look like it is taken by a JavaThread that wants to avoid safepoint checks.

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PR: https://git.openjdk.java.net/jdk/pull/5323