How to profile Native JNI library

Question

How can I profile a Java Native Interface library written in C?

I know about the usual C profilers, but my question is how can I profile the whole set including the calls to the JVM methods which might be slowing down the program.

Answer 1

After some research and testing with some of the methods proposed here I ended up using sprof.

Basically I followed the instructions available in this answer. Some comments:

1. I had to leave LD_PROFILE_OUTPUT empty in order to get the result in /var/tmp/, otherwise the output file was not generated.
2. I assigned LD_PROFILE=libXXXX.so

To get the profile I ran the Java code which loads and uses the native JNI library and I got a file with the profiling results in:

/var/tmp/libXXXX.so.profile

Once you have the file you can read it using the command:

sprof /path/to/libXXXX.so /var/tmp/libXXXX.so.profile

The results of the profiling follow the same template as gprof. Here you can find a description of the contents and their meaning.