Loading native libraries

Question

Hi,
The other day a came across an UnsatisfiedLinkError with the message "... already loaded in another classloader". I saw the JNI specification states a native library is only permitted to be loaded by a single classloader. My question is why is this the case? What if I have two indipendent applications running on the same JVM instance, and both rely on the same native library? the problem with these native libraries is that there is no classloader delegation architecture when loading one(as there is with java classes), the library will always be loaded by the calling classes' classloader. So what can a developer do? What is the idea behind this behavior?
Any help is appreciated....

Answer 1

Thanks for your answers,
The thing is -
1) I don't really want to load the library again, I
simply wish there will be no exception if I attempt to
load it again from a different classloader. After all,
what does it matter from which classloader i try to
load the library? If it is the same classloader the
method will simply return as if it loaded the lib
succesfully(even though it didn't since it detected
it's already loaded), why should there be any
difference if it's not the same classloader? the
library is already loaded anyway, all classes in the
JVM instance will have access to it anyway....Write the code so that it checks for the already loaded exception.
2) What if I one of my applications is a "third party"
app in which I cannot change the code to load the
library through my "library loader"?You are probably out of luck.
Although I would question why you would want a third party library used by mutliple applications to be individually loaded. In J2EE containers the database drivers are loaded outside the class loaders probably for similar reasons.