Re: [fedora-java] Hadoop + log4j2 = fullstop

[Mat Booth]

On 21 May 2014 17:03, Robert Rati <rrati(a)redhat.com&gt; 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