Hi Thomas, very positive suggestion.
One observation: There already seems to be some different interpretation of the command line in different Java versions: For instance when I try to dump a flight recording in 1.8.0_152-ea-b05 : I can use: jcmd 33014 JFR.dump filename="recording1.jfr" recording=1 but in build 9+181 , the same command must be: jcmd 33014 JFR.dump filename="recording1.jfr",recording=1 (the comma to separate sub-options you mentioned earlier) Therefore the suggestion without curly brackets, giving several commands after one another seems good with regard to backwards compatibility. Motivation: hawt.io uses the MBean com.sun.management:type=DiagnosticCommand to access the same functionality as jcmd. Variations in option syntax across Java versions is already an issue (only affecting sub-options though, as each command is a separate JMX operation). So syntax compatibility is highly appreciated :-) Martin lør. 12. mai 2018 kl. 20:11 skrev Kirk Pepperdine <kirk.pepperd...@gmail.com >: > > > On May 10, 2018, at 11:26 AM, Thomas Stüfe <thomas.stu...@gmail.com> > wrote: > > > > On Thu, May 10, 2018 at 9:13 AM, Kirk Pepperdine > > <kirk.pepperd...@gmail.com> wrote: > >> The stacking at the safe point would be a huge win. Right now thread > dump consistency can really confuse people as the tooling will show two > threads owning the same lock at seemingly the same time. Reality, it’s just > that people didn’t realize you get a safe point for each thread therefor > there is motion in the system as you’re collecting the data. > > > > I am a bit confused. What tooling are you talking about? > > jstack. I’ve not seen it with jcmd. But I often see 2 threads holding the > same lock at the “same time” which is of course non-sense. I can dig one up > for you if you’re still confused. > > > > > >> > >> As an aside, it’s amazing how many dev’s aren’t aware of jcmd. Just > yesterday after my session at Devoxx I had someone ask me about using jfr > from the command line, many in that session had not seen jcmd before. The > feedback was, wow, this is very useful and I wished I had of known about it > earlier. > > > > Yes, jcmd is quite useful. I also really like the simple design, which > > is by default up- and downward compatible (so you can talk to any VM, > > new, old, it should not matter). That is just good design. We - Sap - > > work to extend jcmd, to help our support folks. E.g. the whole new > > VM.metaspace command chain. > > And simple it is….well done!!! > > — Kirk > >
