jcmd - executing multiple commands at the same safepoint?

[Thomas Stüfe]

Hi Kirk,

On Thu, May 10, 2018 at 8:07 AM, Kirk Pepperdine
<kirk.pepperdine at gmail.com> wrote:
>
>> On May 10, 2018, at 7:04 AM, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
>>
>> Oh... maybe. You are right. And I see commas are not good either since
>> they are used in sub options (e.g. GC.class_stats).
>>
>> Alternative ideas could be using brackets surrounding the
>> command-and-options (e.g. '{''}'):
>>
>> jcmd  { GC.class_stats columns=InstBytes,KlassBytes }  { VM.metaspace
>> show-loaders }
>
> are exposed braces safe in shells?
>>
>> I think technically we would not even need delimiters, since the
>> commands are as keywords limiting enough. E.g. one could just specify:
>>
>> jcmd  GC.class_stats columns=InstBytes,KlassBytes VM.metaspace show-loaders
>
> I’d vote for this form. Simple..

I think so too.

Note how it would influence the form of jcmd command files:

<command 1>
<command 2>
would execute two commands sequentially at different safepoints

<command 1> <command 2>
would execute two commands at the same safepoint

Arguably though, if we can stack commands at the command line, the
jcmd file gets less important.

I'll play around a bit and wait what others say.

Thanks, Thomas

>
> — Kirk
>
>>
>> and that would be for jcmd too. It is more for the benefit of the user.
>>
>> On Thu, May 10, 2018 at 7:54 AM, Kirk Pepperdine
>> <kirk.pepperdine at gmail.com> wrote:
>>> Awesome idea! Would the semicolon would be an issue for shell scripts?
>>>> On May 10, 2018, at 6:52 AM, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
>>>>
>>>> Hi all,
>>>>
>>>> just asking around for opinions.
>>>>
>>>> I am playing with the idea of bundling diagnostic commands to have
>>>> them executed at the same safepoint, in order to get results
>>>> consistent with each other.  E.g. a heapdump and a corresponding
>>>> metaspace statistic.
>>>>
>>>> Syntax wise, I think one could specify multiple commands in jcmd
>>>> separated by comma or semicola:
>>>>
>>>> jcmd <command> <option> <option>; <command 2> <option> <option>
>>>>
>>>> What do you think, would that be a useful addition?
>>>>
>>>> Thanks, Thomas
>>>
>