[RFR]: Per thread IO statistics in JFR

Lindenmaier, Goetz goetz.lindenmaier at sap.com
Fri Feb 1 12:06:35 UTC 2019


Hi Alan, 

Are you referring to this?
8148188: Enhance the security libraries to record events of interest
http://hg.openjdk.java.net/jdk/jdk12/rev/f7309a1491d9

Which, presumably, needed this
8203629: Produce events in the JDK without a dependency on jdk.jfr
http://hg.openjdk.java.net/jdk/jdk12/rev/a181612f0715?revcount=40

Best regards,
  Goetz.


> -----Original Message-----
> From: Alan Bateman <Alan.Bateman at oracle.com>
> Sent: Freitag, 1. Februar 2019 12:37
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>
> Cc: hotspot-jfr-dev at openjdk.java.net; Java Core Libs <core-libs-
> dev at openjdk.java.net>; Hotspot dev runtime <hotspot-runtime-
> dev at openjdk.java.net>
> Subject: Re: [RFR]: Per thread IO statistics in JFR
> 
> On 01/02/2019 11:19, Lindenmaier, Goetz wrote:
> > :
> > 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.
> >
> Erik Gahlin put in support in JDK 12 to allow for code in java.base to
> generate JFR events. I think the only user so far is in the security
> area where there are events to log usages of weak crypto. I think this
> is one of the approaches that will need to be looked at as part of the
> exploration on the right way to add serviceability support to the libraries.
> 
> -Alan



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