RFR: JDK-8261034: improve jcmd GC.class_histogram to support parallel

[Chris Plummer]

On Fri, 19 Feb 2021 05:17:43 GMT, Hamlin Li <mli at openjdk.org> wrote:

>"Degree of parallelism for heap iteration. "

How about "Number of parallel threads to use for heap inspection". I've noticed the term "heap iteration" in a few places, but I think "heap inspection" would be better. That would be inline with terminology used in the source:

 130   VM_GC_HeapInspection(outputStream* out, bool request_full_gc,
 131                        uint parallel_thread_num = 1) :

For the rest of the help:

"0: let the VM determine the number of threads to use. "
"1: use one thread, i.e. disable parallelism. "
"<n>: Request that <n> threads be used. <n> must be positive. The VM will try to use <n> threads, but might use fewer threads than <n>."

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PR: https://git.openjdk.java.net/jdk/pull/2379