On Sat, 20 Feb 2021 03:27:22 GMT, Chris Plummer <[email protected]> wrote:
>>> BTW, we have three PRs related to `parallel=<n>`. I think it would be best
>>> to hold off pushing any of them until they have all been reviewed and
>>> approved. One reason is because the `parallel=<n>` output should be
>>> consistent for all of them, and if there is a minor suggestion for a change
>>> in one, it should be applied to all 3.
>>
>> Sure, will hold off.
>> Summarize the help messages as below:
>> "Number of parallel threads to use for heap inspection. "
>> "0: let the VM determine the number of threads to use. "
>> "1: use one thread, i.e. disable parallelism. "
>> "n: Request that threads be used. n must be positive. The VM will try to use
>> n threads, but might use fewer threads than n."
>
> For jmap -histo we have:
>
> parallel=<number> parallel threads number for heap iteration:
> parallel=0 default behavior, use predefined
> number of threads
> parallel=1 disable parallel heap iteration
> parallel=<N> use N threads for parallel
> heap iteration
>
> It's a bit inconsistent here in that it says <number>, <N>, and N. I'd like
> to see that cleaned up at some point along with a few other things (as part
> of a separate PR). However, my point is that the value of the argument is
> given a name, <number> in this case, so it can be referenced in the help
> output. However, jmap help is done differently than jcmd help, which doesn't
> give names to the value of options. For example, GC.heap_dump has:
>
> Options: (options must be specified using the <key> or <key>=<value> syntax)
> -all : [optional] Dump all objects, including unreachable objects
> (BOOLEAN, false)
> -gz : [optional] If specified, the heap dump is written in gzipped
> format using the given compression level. 1 (recommended) is the fastest, 9
> the strongest compression. (INT, 1)
>
> The -gz option is much like -parallel in that a value is given for it, but
> there is no "name" for that value in the help output. So maybe we should
> avoid calling it "n" or <n>, or anything like that:
>
> "Number of parallel threads to use for heap inspection."
> "0 (the default) means let the VM determine the number of threads to use. "
> "1 means use one thread (disable parallelism). "
> "For any other value the VM will try to use the specified number of threads,
> but might use fewer."
>
> I think we can leave out "Must be positive." It should be obvious, and I
> assume an error is generated if negative number is given.
Sure, thanks for the detailed reviewing.
Let me record the help message as below:
"Number of parallel threads to use for heap inspection."
"0 (the default) means let the VM determine the number of threads to use. "
"1 means use one thread (disable parallelism). "
"For any other value the VM will try to use the specified number of
threads, but might use fewer."
-------------
PR: https://git.openjdk.java.net/jdk/pull/2379
