[fedora-java] Hadoop + log4j2 = fullstop

[Mat Booth]

On 21 May 2014 17:03, Robert Rati <rrati at redhat.com> wrote:

> I've been working on updating the hadoop package to the latest 2.4.0
> release and at this point I've resolved all the issues but I'm now blocked
> by the log4j2 update.  log4j2 breaks the hadoop build pretty severely, and
> it doesn't seem the log4j2 team has spent much time thinking about how to
> provide backwards compatibility to existing log4j1.2 users.  From my
> investigation of log4j2:
>
> log4j.properties file is no longer read at all
> configuration file is now in XML or JSON
> configuration file name is log4j2.[xml|json|jsn]
> V2 isn't backwards compatible with V1.  There's a shim for v1 api but it
> will only work for a limited set of cases, and for some cases it does work
> for it turns some operations into noop calls.
>
> This is a pretty major change and even the compatibility layer, if it will
> work for a project, does not seem to guarantee like functionality and
> minimally will require a re-do of all log4j configuration files a project
> ships.  I'm not sure many sizable upstream projects would undertake/accept
> such a drastic change very quickly.
>
> The list of projects currently blocked by this update are:
> hadoop
> hbase
> oozie
> hive
> apache-log4j-extras
> amplab-tachyon
>
> I would be surprised if there aren't a lot more.  I understand Fedora is
> always pushing for the latest versions, but for some fundamental packages
> can there be compatibility packages introduced at the same time as an
> incompatible update?  Package maintainers of dependent packages will still
> need to touch their packages and determine if the new version will work for
> them.  Providing a compat package will also allow packages to update to
> their newer versions while not held up on trying to integrate changes from
> a compatibility breaking dependency update.
>
> Rob
> --
>

Yes, there are precedents for compat packages.  For example there are both
jdom and jdom2 packages in Fedora for this reason. There also used to be a
xml-commons-apis12 compat package (not any more though, we were able to
finally retire it in favour of xml-commons-apis.)


-- 
Mat Booth
http://fedoraproject.org/get-fedora
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