[RFR]: Per thread IO statistics in JFR

[Lindenmaier, Goetz]

Hi,

> These features are orthogonal. Please read Gunter's answer about the
> difference in his previous mail
> (https://mail.openjdk.java.net/pipermail/core-libs-dev/2019-
> January/058030.html)
> repeated here for your convenience:
> 
> "The existing events are triggered only if the time the IO operation
> takes, exceeds a threshold (10ms/20ms for profile/default settings
> respectively). They are aimed for providing information on the time IO
> operations take and do not provide per thread IO statistics. What we
> are interested in is per thread information similar to the
> jdk.ThreadAllocationStatistics event."
To kick in here, too:
The existing solution tells you which threads spend a lot of time
in IO operations. This is a good hint to problems in the infrastructure. 
You might just write a few bytes, but still get long delays because the 
disc is too slow or saturated etc.
The numbers Gunter collects give information about what your
code intends to do: how much bytes does the code write? Should
you optimize your application to communicate less?  ... to write
less to file?

If you have both numbers, you can even better recognize threads
that wait too long on the network: they write few bytes but still
spend a lot of time in the calls.

So I see enough arguments to have both metrics.

Best regards,
  Goetz.








> 
> > So overall I think there
> > is a lot to discuss and write-up.
> >
> 
> Sure, lets discuss this in Brussels at the Committers workshop :)
> 
> Regards,
> Volker
> 
> > -Alan