Updates to JEP-158: JVM Unified Logging are coming...

Martijn Verburg martijnverburg at gmail.com
Fri Apr 17 10:12:55 UTC 2015

Hi Fredrik,

Thanks from us (jClarity and some other orgs) for considering the tag based
system, we're really glad you've gone in this direction.  One quick bit of

Is it possible to add a binary / compressed logging format or an interface/
API to plug one in for high performance Logging?  Human readable is nice
for looking at logs immediately, but for some of our customers they'd be
looking to offload that concern to another process/host.


On 17 April 2015 at 09:32, Fredrik Arvidsson <fredrik.arvidsson at oracle.com>

> Hi
> We are planning to release an updated version of JEP-158 very soon. The
> work to update this JEP has been going on for some time and we now feel we
> are ready to present it to a wider audience.
> The JEP for JVM Unified Logging was created back in February 2012. The
> requirements for the API and implementation were heavily influenced by the
> logging functionality in JRockit JVM. The JEP was updated and refined in
> mid 2014 and eventually targeted for JDK 9 in late 2014:
> https://bugs.openjdk.java.net/browse/JDK-8046148
> During the review process of the JEP some concerns were voiced about the
> chosen API and functionality but the conclusion was that the proposal would
> work, and the JEP was targeted for JDK 9 and the implementation work was
> started.
> Early 2015 during pre-reviews and presentations of the API and
> implementation concerns were again raised about the formulation of the JEP,
> this time with greater force. At this point we decided to take a time-out
> and investigate our options going forward.
> The time-out led to a modified proposal that can be found here:
> http://cr.openjdk.java.net/~farvidsson/JEP-158/JEP-158.html
> and with some illustrations here:
> http://cr.openjdk.java.net/~farvidsson/JEP-158/JEP-158_Illustration.png
> So what have we changed, and why?
> In short we have switched from using an hierarchical log subject layout to
> something that could be best described as a tag based solution.
> The main reason for the change of the logging API is that we have found
> that some logging can't easily be ordered under a single hierarchical
> subject but can belong to multiple subjects/areas. One example of this is
> logging in the 'metaspace' code. The functionality in the 'metaspace area'
> can be called from both GC and Runtime code. Another example is
> class-unloading. There are more examples on this of course, but these two
> we think are very clear and easy to understand.
> The core functionality of the logging framework is not changed that much
> from the earlier proposal. We have tried to make it leaner and not as
> verbose (functionality wise) as before. The scope of the implementation has
> been narrowed down some to enable us to deliver good value as soon as
> possible.
> Our plan is as follows:
> After getting initial feedback from the community about the new proposal
> we will update the JEP description. We aim to do this early next week.
> We are planning to use the JDK9 sandbox repository during development.
> This enables us who are implementing it to work in an efficient way and at
> the same time it allows any interested party to try out and follow the work
> during the implementation phase.
> More information about the sandbox repository name and other
> practicalities will follow shortly.
> Cheers
> Fredrik Arvidsson & Marcus Larsson, JVM Serviceability, Stockholm.

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