perfsonar development work

[Szymon Trocha <>]

Hi all,

Working on Berlin meeting demo I just found out that one could not run 
two RRD MA services at the same time. See below:

> >> Both services run on the same machine and should use the same library.
>
> Here is the reason in not-working RRD MA log:
>
> 2008-06-19 10:45:49,821 ERROR - RRDStorageManager.rrdFetch: Cannot 
> connect with rrdjtool native library: Native Library /opt/perfson
> ar/services/geant2-java-rrd-ma/WEB-INF/contrib/rrdjtool/build/libjrrd.so 
> already loaded in another classloader

Wow, this is a catch. It seems two RRD MA can't coexist due to JNI design!

http://java.sun.com/docs/books/jni/html/design.html

11.2.4 A Type Safety Restriction

The virtual machine does not allow a given JNI native library to be 
loaded by
more than one class loader. Attempting to load the same native library by
multiple class loaders causes an UnsatisfiedLinkError to be thrown. The
purpose of this restriction is to make sure that namespace separation 
based on
class loaders is preserved in native libraries. Without this restriction, it
becomes much easier to mistakenly intermix classes and interfaces from
different class loaders through native methods.


Regards,
Nina


--
Szymon Trocha

Poznan Supercomputing & Ntw. Center ::: NETWORK OPERATION CENTER
Tel. (+48 61) 8582022
http://noc.man.poznan.pl  ::: http://noc.pionier.gov.pl