[prev in list] [next in list] [prev in thread] [next in thread] 

List:       openjdk-serviceability-dev
Subject:    Re: [RFR]: Per thread IO statistics in JFR
From:       "Haug, Gunter" <gunter.haug () sap ! com>
Date:       2019-01-15 10:12:03
Message-ID: FC3E41BC-457A-4058-AED9-89052544E9A7 () sap ! com
[Download RAW message or body]

Hi Erik,

the overhead is very small. In fact, I wasn't able to measure it in a reproduceable \
way. And yes, it works on Mac OS, I use a Mac.

> could change the contentType to "bits-per-second". That is what we use for the \
> Network Utilization event which reports statistics per interface.

Yes, I can do that. Only for the network IO or for file IO as well?

Thanks for looking into this,
Gunter

From: serviceability-dev <serviceability-dev-bounces@openjdk.java.net> on behalf of \
                Erik Gahlin <erik.gahlin@oracle.com>
Date: Monday, 14. January 2019 at 22:32
To: "serviceability-dev@openjdk.java.net" <serviceability-dev@openjdk.java.net>, \
                "hotspot-jfr-dev@openjdk.java.net" <hotspot-jfr-dev@openjdk.java.net>
Subject: Re: [RFR]: Per thread IO statistics in JFR

Hi Gunter, 

Sounds like a useful enhancement!

Do you have an idea of what the overhead might be?  

Does it work on Mac OS X?

I haven't done a proper review, but you could change the contentType to \
"bits-per-second". That is what we use for the Network Utilization event which \
reports statistics per interface.

Thanks
Erik
Hi All,

Could I please have a review and possibly some opinions on the following enhancement \
to JFR and the JDK? 

At SAP we have a per thread IO statistic among our supportability enhancements which \
proved to be very helpful for our support engineers. It might be beneficial for JFR \
as well and would certainly help us to drive adoption of OpenJDK.

The basic idea is simple, we have added fields to the thread class where the number \
of bytes read and written from/to file and network are counted in. The newly created \
JFR events are written periodically as for example the ThreadAllocationStatistics \
event already is.

In order to collect the data, we have added hooks to the JDK C coding calling back \
into the VM.

I have opened a bug here:
https://bugs.openjdk.java.net/browse/JDK-8216981

Here is a webrev:
http://cr.openjdk.java.net/~ghaug/webrevs/8216981

There are no tests yet and the code be a bit nicer in places. We will work on this \
if/when this feature is deemed acceptable.

Finally, we have an API in our SAP version of the JDK to access this data from a Java \
application. This is used by many SAP applications and I think we could add an MXBean \
in a second step, to provide similar functionality.

Thanks in advance,
Gunter


[prev in list] [next in list] [prev in thread] [next in thread]