JEP 271: Unified GC Logging - Third pre-review

ecki at ecki at
Fri Nov 13 10:05:09 UTC 2015

Hello Bengt,

Looks good, one question on the "first line", you write out the gc policy in use, will this be repeatet every time the file is rolled over?

In the current GC logs the VM version and option details had been added. I think this was imensly usefull to have all the important bits at the beginning of each logfile. Can you include that as part of gc tags? (Datestamp, pid, gc selected, vm uptime, log generation, command line arguments and maybe even OS memory details)



-----Original Message-----
From: Bengt Rutisson <bengt.rutisson at>
To: "hotspot-gc-dev at" <hotspot-gc-dev at>
Sent: Fr., 13 Nov. 2015 10:19
Subject: JEP 271: Unified GC Logging - Third pre-review

Hi everyone,

Here is an updated pre-review for the work for JEP 271 Unified GC Logging.

Now it includes all the logging that I plan on converting for the first 

Here are examples from the latest prototype:

The webrev for the changes is available here:

Some changes that have been made:

- GC id is now logged as "GC(5)" instead of the previous "GC#5"
- The CMS and G1 concurrent logging have been homogenized to look 
similar. All concurrent phases are start with "Concurrent" and now 
include timestamps.
- The paused phases now all start with "Pause".
- The log messages from the different collectors now look more similar. 
For example "Pause Young" is used for young GCs for all collectors 
instead of for example "Young pause" for G1 and "Pause. ParNew" for CMS.
- I've added a line at the start of the log to clearly state what GC is 


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