Question

everyone,

Suppose I have a simple JNI program in Windows:

int* p = NULL;
*p = 5;

When run it from JVM, not like normal C++ application, JVM will nicely catch such hard exception and do some cleanup work.

The problem here is it also stops me from generating crash dumps right there, although there is a JVM option: -XX:OnError, but core dumps generated at this point is far from the crime scene thus hard to debug.

JVM wrap each Java thread using SEH:

__try
{
    thread.run()
}
__except(topLevelExceptionFilter())
{
}

JNI code which cause access violation happen in thread.run, but handled in topLevelExceptionFilter, which is already somewhere else.

Do you have any suggestions?

Thanks.

Answer 1

A core is a C++ crash dump… you don’t have the convenience facilities that Java provides to make it easier to work with. If you compiled your native code to retain symbols (and ideally to not be optimized) you can use gdb or another debugger to analyze it and obtain a stack trace at the point of failure, as well as read variables, etc.

core dumps generated at this point is far from the crime scene thus hard to debug — core dumps are not “far from the crime scene” at all, they’re fully comprehensive of the so-called crime scene. The only reason you think they’re hard to debug is it’s something you haven’t learned yet… but they’re definitely the right tool for this job.