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From Jeffrey Janner <>
Subject RE: Best practices for shared classloader use?
Date Thu, 06 Jun 2013 13:40:47 GMT
> -----Original Message-----
> From: []
> Sent: Tuesday, June 04, 2013 11:25 AM
> To: Tomcat Users List
> Subject: Re: Best practices for shared classloader use?
> Hi Don!
> Usually each Webapp has its own classloader thus two webapps can have
> different versions of the same class. Classloaders are chained so if a
> class is not found search continues in the next classloader. Shared
> just means one classloader is used by different webapps thus you may
> run into trouble if each webapp requires a different class version
> (changed method signature) as you can not predict which version you
> get. As long you can align the shared libs across all webapps this is
> not an issue. I do not see your static field problem, though?
> Share functionality like using the same jars? If all use the same
> version you can push it to the shared imho.
> Jens

Statically declared variable are a big problem with the shared class loader.
Check the archives for this topic. You only need to go back a month or two.
If you doubt me, try sharing log4j among a bunch of apps, each with its own properties file.
Then try to figure out where the messages are going (hint: it will be only 1 of the files).

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