JNI memory management using the Invocation API

Question

When I\'m building a java object using JNI methods, in order to pass it in as a parameter to a java method I\'m invoking using the JNI invocation API, how do I manage its me

Answer 1

The GC would collect your instance, but it will not automatically release the non-java heap memory allocated in the native code. You should have explicit method in your class to release the c_object instance.

This is one of the cases where I'd recommend using a finalizer checking if c_object has been released and release it, logging a message if it's not.

A useful technique is to create a Throwable instance in the Java class constructor and store it in a field (or just initialize the field inline). If the finalizer detects that the class has not been properly disposed it would print the stacktrace, pinpointing the allocation stack.

A suggestion is to avoid doing straight JNI and go with gluegen or Swig (both generate code and can be statically linked).