Exit handling in native function by JNI

Question

Hi everyone,
We are developing a Java application using native function calls through JNI in Linux.
The application starts and calls a native function and the native function attach a signal
handler and an exit handler. In addition, in the native function, we fork another process
and in the forked process, we calls a several java-side methods. It works in normal cases.
However, when System.exit() is called in the java-side methods invoked by a native function,
the application is stopped. Thus we add shutdown hook (Runtime.getRuntime().addShutdownHook())
to treat this case. The shutdown hook just calls a native method, and the native method
just calls exit(). We expect the calling exit() in the native method invoked in shutdown hook for JVM
invokes our exit handler which is attached in advance. It looks working well.
But, sometimes we find several garbage(?) jvm processes (we can see the process named as "java"
in using Linux command "ps"). The parent process of these processes is init process (pid = 1).
With the pid of these processes, we suspect the processes are created when we fork another process
in native function invoked through JNI. However it is not happened every times in our application.
Why the garbage java processes remain? Is there any problem in the calling exit() in the native
method invoked during JVM Shutdown process?
I hope any answers for this problem.
Thanks in advance,
Seung-Uk Oh

Answer 1

Thus we add shutdown hook
(Runtime.getRuntime().addShutdownHook())
to treat this case. The shutdown hook just calls a
native method, and the native method
just calls exit(). We expect the calling exit() in the
native method invoked in shutdown hook for JVM
invokes our exit handler which is attached in advance.
It looks working well.I wouldn't think that was a good idea.
You are terminating the JVMs normal exit process. Why don't you just register the exit processes in your own stack and call them with the native method?