CODEWITHSUNDEEP
websphereclassloader
Bastl
Bastl

Reputation: 3006

Websphere: Does parent_last affect other applications?

Does parent_last affect other applications ? Is my application using parent_last affected by other applications?

The server is set to "Multiple Classloaders" (one for each application IIUC).

In my understanding, this would mean that all classes are loaded from the application, correct?

What happens if another application loads a class present in websphere extensions, and lateron my application uses that class. Will it be reloaded, or will the one from parent be used? (it might be incompatible to the classes in my application).

The websphere manual says:

"By specifying Classes loaded with local class loader first (parent last), your application can override classes contained in the parent class loader, but this action can potentially result in ClassCastException or LinkageErrors if you have mixed use of overridden classes and non-overridden classes."

But I do not understand this potential risk. Can somone please provide examples for this?

Upvotes: 0

Views: 522

Answers (1)

ﾤ ﾡ
ﾤ ﾡ

Reputation: 5782

Classes loaded by application class loader cannot interfere in any way with those loaded by other applications since application classloaders are isolated from each other.

The quote that you provided warns about potential problems that might occur when libraries have transitive dependencies. For example, your application uses libraryA that depends on libraryB. LibraryA is some sort of "standard" library provided by application server, so you don't package it with the application. Then, if for some reason you need to have libraryB in the application and the version of it is different from the one expected by libraryA, you might have problems with incompatibility.

Upvotes: 1

Related Questions