JEP 271: Unified GC Logging - First pre-review

[Staffan Friberg]

Just skimmed so far, will give it a more through look.

Do we want to keep the space after the the Times output? Does it add any 
value?
Can bite you sometimes when you grep and look for line endings.

"[Times: user=0.10 sys=0.00 real=0.02 secs] "

//Staffan

On 10/26/2015 05:26 AM, Bengt Rutisson wrote:
>
> Hi again everyone,
>
> An update on the work for JEP 271 Unified GC Logging.
>
> I now have a working prototype that covers all GCs. Here are some 
> examples comparing the old format (using -XX:+PrintGC and 
> -XX:+PrintGCDetails) with the new format (using -Xlog):
>
> http://cr.openjdk.java.net/~brutisso/JEP-271/pre-review.00/compare.html
>
> The new logging format, using -Xlog, is much more flexible than the 
> old format. So, the comparison table on the above page is by no means 
> complete. I hope it will give a good overview, but to get a real feel 
> for how the new logging works I think it is necessary to run locally 
> and play around with the logging options.
>
> Here is a webrev of the changes so far:
> http://cr.openjdk.java.net/~brutisso/JEP-271/pre-review.00/webrev.00/
>
> There is still work to do and I have some known issues with the code 
> changes. So, I am currently not asking for too much feedback on the 
> actual code changes. I am more looking for feedback on the logging 
> behavior. The webrev can be useful to get a feel for what the code 
> changes will look like but mostly I think it can be used to apply the 
> patch and build your own HotSpot to try out the new logging.
>
> Some changes based on the initial feedback:
> - Start and end timestamps for the GC included on the GC log line.
> - Printing the unit of a value without a space. I.e. "10.345ms" 
> instead of "10.345 ms". (Still working on fixing this in all places as 
> well as trying to use milliseconds instead of seconds in as many 
> places as possible.)
> - Printing heap change information with a fixed unit. I am now using M 
> for overall heap transition and K for detailed information on the 
> debug level.
> - Removed the "summary" tag. Instead the end logging for a GC includes 
> all relevant information.
>
> All feedback is very welcome!
>
> Thanks,
> Bengt