RFR (L): 8046148: JEP 158 Unified JVM Logging

Ioi Lam ioi.lam at oracle.com
Mon Sep 14 16:01:53 UTC 2015

On 9/14/15 6:18 AM, Marcus Larsson wrote:
> On 2015-09-11 15:51, Coleen Phillimore wrote:
>> I'm not a big fan of having these blanks in the logging lines. I 
>> don't think making the line length longer is going to be helpful and 
>> what people are looking for is the message at the end, not which tag 
>> and level they used.  I think they look kind of strange.
>> Coleen
> While it might look a bit weird, I think it can help readers to 
> quickly find the start of the actual log message. Maybe we could leave 
> it as it is for now, deferring the decision if we want the padding or 
> not until we have some real logs to look at. If we find the padding 
> inconvenient at that point we can just remove it in a follow-up RFE.
I agree. Eliminating the extra spaces is quite easy with a sed script. 
It's harder to use a script to add the spaces back to align the output.

- Ioi

> Thanks,
> Marcus
>> On 9/11/15 9:40 AM, Marcus Larsson wrote:
>>> Yes, decorators are padded to avoid jagged logs and help 
>>> readability. Since the levels are known beforehand, a fixed padding 
>>> is used for that decorator. For other decorators such as tags or 
>>> timestamps, the padding will grow to the size of the longest (so 
>>> far) seen decoration. This means the decorator prefix length will 
>>> either stay the same or increase, but never decrease. After a while 
>>> it should stabilize around some fitting length and not grow 
>>> significantly.
>>> For example:
>>> [0.655s][debug  ][safepoint] Safepoint synchronization initiated. (20)
>>> [0.656s][debug  ][safepoint, some_other_tag] Safepoint 
>>> synchronization initiated. (20)
>>> [0.657s][debug  ][safepoint,               ] Safepoint 
>>> synchronization initiated. (20)
>>> [10.657s][debug  ][safepoint,               ] Safepoint 
>>> synchronization initiated. (20) \ 

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