Debug Assertion from javaw.exe

Question

I'm getting a Debug Assertion Failed from javaw.exe: (Windows 2000)
jre1.4.2\bin\javaw.exe
File: dbgheap.c
Line 1044
Expression: _CrtIsValidHeapPointer(pUserData)
This occurs on one of my native DLL method calls. Here's the scenario:
I've got a set of supplied DLLs from a manufacturer that are implemented using C++ and STL. I'm working on a wrapper DLL that maps to a Java class in that my Java class invokes the appropriate native methods in my wrapper DLL, which in turn works with the supplied vendor DLL's.
As part of the initialization, I load up my wrapper DLL, and invoke its initialize() method, which in turn instantiates a C++ object:
DShowLib::Grabber* m_pGrabber;
JNIEXPORT void JNICALL Java_biz_femtosoft_rtfrog_data_framegrabber_ImagingSourceFWFrameGrabber_initialize
(JNIEnv *, jobject)
     if( !DShowLib::InitLibrary( "********" ) )
          fprintf( stderr, "The library could not be initialized ");
          fprintf( stderr, "(invalid license key?).\n");
          exit( 1 );
     m_pGrabber = new DShowLib::Grabber();
     fprintf( stdout, "[DEBUG] The library has been initialized \n");
Note that this C++ object is referenced by a global variable, m_pGrabber.
In a subsequent function in my wrapper DLL, I invoke a method on the instantiated C++ object, and that is where the debug assertion happens:
JNIEXPORT jobjectArray JNICALL Java_biz_femtosoft_rtfrog_data_framegrabber_ImagingSourceFWFrameGrabber_jni_1getVideoCaptureDevices
(JNIEnv *env, jobject)
     fprintf( stdout, "[JNI FRAMEGRABBER] Entering getVideoCaptureDevices JNI function call\n");
     if (m_pGrabber != 0) {
          // Generate a list of all available video devices
          DShowLib::Grabber::tVidCapDevListPtr pVidCapDevList = m_pGrabber->getAvailableVideoCaptureDevices();
I've omitted much of the source for brevity.
Can anyone tell me what I might be doing that's causing this? I'm pretty rusty on my C++ coding, so there's a good chance that I am forgetting something quite fundamental.
Regards,
Ron Cordell

Answer 1

Ok, I've discovered the -Djava.library.path command line switch. That took care of the problem.
Now I can see where things fail, and it is on the return that the exception occurs. The code that is executing is shown below. Upon execution of the return 0 statement, I get the Debug Assertion Failure. Is it because there is some local storage hanging around?
JNIEXPORT jobjectArray JNICALL Java_biz_femtosoft_rtfrog_data_framegrabber_ImagingSourceFWFrameGrabber_jni_1getVideoCaptureDevices
(JNIEnv *env, jobject)
     fprintf( stdout, "[JNI FRAMEGRABBER] Entering getVideoCaptureDevices JNI function call\n");
     if (m_pGrabber != 0) {
          // Generate a list of all available video devices
          DShowLib::Grabber::tVidCapDevListPtr pVidCapDevList = m_pGrabber->getAvailableVideoCaptureDevices();
return 0;
}