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From saurabh tiwari <saurabhtiwar...@gmail.com>
Subject Re: Tomcat 8 classloading
Date Wed, 13 Jul 2016 12:11:31 GMT
Thanks a lot Chris.

Thanks,

Saurabh Tiwari
9158483338

On Wed, Jul 13, 2016 at 1:49 PM, chris derham <chris@derham.me.uk> wrote:

> > Hi There,
> >
> > We are about to upgrade from tomcat-7.0.65 to tomcat-8.0.XX. and this is
> > regarding the loading of same JARs within the different application. to
> > understand the scenario, consider below case
> >
> > Tomcat 8 ---
> >         webapps
> >             a.war--> lib--> spring.jar
> >             b.war--> lib--> spring.jar
> >
> > here b.war is just a copy of a.war and renamed just to differentiate
> hence
> > spring.jar is same for both the applications.
> >
> > My question is
> >
> > 1) will spring.jar loaded twice
>
> yes it will be loaded twice
>
> > 2) how to i make sure to load it only once ( if loaded twice)
>
> This question comes up frequently. Search the mailing list for shared
> class loader to see the details. The upshot is that this can be done
> using shared class loader, however there are real technical issues if
> you do this - class cast exceptions, difficulty performing upgrades to
> individual wars without taking down all of tomcat. The only positive
> is that you might save a few MB of memory cost by having the same jar
> loaded twice in memory.
>
> I've been on this mailing list for ~8 years, and every time this
> issues comes up (about 5 times a year?), the tomcat developers suggest
> that the proposed memory saving isn't not worth the problems that it
> causes..
>
> HTH
>
> Chris
>
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