[External] : Re: 8340363: Tag-specific default decorators for UnifiedLogging

[Anton Seoane Ampudia]

Hello,

This proposal is targeted only for those cases where Hotspot developers agree on undecorated output. For example, C2 developers with jit+inlining. Every other use of UL except for those specific (and previously socialized and agreed-upon) cases will keep being the same as it is right now.

In summary, this is more of an ad-hoc proposal for the cases where some specific uses of -Xlog are always accompanied with ::none

Regards,
Antón

From: Kirk Pepperdine <kirk at kodewerk.com>
Date: Monday, 30 September 2024 at 18:07
To: Anton Seoane Ampudia <anton.seoane.ampudia at oracle.com>
Cc: David Holmes <david.holmes at oracle.com>, hotspot-dev at openjdk.org <hotspot-dev at openjdk.org>
Subject: [External] : Re: 8340363: Tag-specific default decorators for UnifiedLogging


So to be clear, is the proposal now to just drop the default decorators,
rather than allowing them to be replaced with alternate defaults? If
that is the case then it is the same as writing:

-Xlog:A+B::none

and I don't really see much value in that. But I wouldn't oppose it.

I would. At a minimum you need a timestamp.


Allowing new defaults gives more flexibility - but obviously the
developers using the specific tag combinations have to agree on what
defaults to set.

At the moment to get a reasonable GC log for G1, one needs to use the following setting.

-Xlog:gc*,gc+ref=debug,gc+phases=debug,gc+age=debug,safepoint:file=gc.log

Also, the “noise to signal” ratio in these logs is exceptionally high.

Kind regards,
Kirk
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