RFR: 8223498: Add Sum of Duration to the jfr summary command

[Chihiro Ito]

Until the jfr tool was created, the only way a user could see a jfr file 
was through JMC. Therefore, when a failure occurs, the user must open 
all JFRs in the JMC for viewing.
Therefore, users want to be able to use the jfr tool to narrow down the 
jfr files they should see in the JMC. This allows users to see fewer jfr 
files using JMC.
I have used JFR on a cluster of hundreds of Java processes, but it was 
very hard to see all the jfr files to figure out the cause.

JMC had the ability to display the total duration, which was very useful.
In my experience, I never use default.jfc or profile.jfc as is. All 
events indicating that threads cannot be used effectively should be 
logged without a threshold. I also limit the threads displayed in the 
JMC to those that are processed by the application.
In such a situation, looking at the total duration is very useful for 
analyzing what is happening in the application. The application may be 
monitoring by code hidden in the library, or it may be sleeping a thread.

I did not consider the 80 character limit. I think limiting the width is 
very useful for people to see. Instead of displaying nanosecond values, 
I will devise something.
I'm very excited about future enhancements. It would be great if we 
could provide common requests as standard functions.

Regards,
Chihiro



On 2019/05/08 22:55, Erik Gahlin wrote:
> I don't see a benefit of adding a sum of duration column.
>
> Events have thresholds. For example, the jdk.JavaMonitorWait event is 
> only recorded if the event exceeds 20 ms so the sum would not be the 
> actual sum. Also, things often happen in multiple threads which makes 
> it hard to know what the value actually means.
>
> The 'jfr' tool tries to not exceed 80 characters (to avoid wrapping), 
> which is hard if another column is added. This especially true if user 
> defined events are added with a longer namespace than "jdk."
>
> The longer term plan is to add a more advanced command where users can 
> aggregate data on arbitrary field and not just the sum as an aggregate 
> function. Users would then be able to aggregate duration per event 
> type, if they really wanted it.
>
> Erik
>
>> Hi,
>>
>> Could you review this enhancement, please?
>>
>> This enhancement adds the total duration of each event to the jfr 
>> summary command to help the user determine which events to display in 
>> the jfr output.
>>
>> webrev:
>> http://cr.openjdk.java.net/~cito/JDK-8223498/webrev.00/ 
>> <http://cr.openjdk.java.net/%7Ecito/JDK-8223498/webrev.00/>
>>
>> jbs:
>> https://bugs.openjdk.java.net/browse/JDK-8223498
>>
>> I have passed the tests in test/jdk/jdk/jfr.
>>
>> Best regards,
>> Chihiro
>
>