Loading JNI library on Tomcat startup

Question

I am trying to load a JNI library on startup of servlet. I have written the following code in my servlet init function:
public void init(ServletConfig config) throws ServletException {
super.init(config);
log.info("Loading native libraries...");
System.loadLibrary("foo");
log.info("Native libraries loaded...");
On Tomcat startup, I see the "Loading native libraries..." message, but I don't see the "Native libraries loaded...". As if the system hung in the System.loadLibrary function.
Anybody knows how to solve this problem?
Martin

Answer 1

The specification specifically forbids the use of native libraries in container objects. So you might want to take that into consideration with whatever you are doing.
If you do want to do that then I would suggest loading it outside of the container. There is probably some configuration option that allows you to force tomcat to load something on start up.
You might also want to consider if hot deploys are part of your future. If they are then you might want to put the interface inside of your own custom class loader, so you can probably control the unload of the shared library.
If you search the J2EE lists you will find that almost everyone states that JNI should not even be loaded into the server. Instead you should create a seperate application and use RMI to access it. Myself I think that is overkill, but I would probably consider exactly what I am interfacing to before making that final decision. If your JNI library blows up it will take down the entire server (which is why the spec forbids it.)