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Thread: JVM crashing on Method call

  1. #1
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    Default JVM crashing on Method call

    Hi,

    I'm currently trying to get a Java-Implementation for the Recast-Navigation Project to work on Windows. The Java-side Library and the JNI-Code is not written by myself. But the author was only able to compile the native library for Linux, as he doesn't own Windows. So I wanted to help him and tried to compile the Library for Windows. I included the c++ files from the Original project and the Wrapper made with SWIG (also made by the author of the Java-Port). I then compiled it with the g++ compiler using cygwin.
    But when I try to call the native Library from Java the JVM crashes every time. With the JVM option "-verbose:jni" I discovered that the crash happened most times after calling one method (rcAllocHeightfield()).
    I did some tests:
    1) I removed all the code from the method of the native library. Then the JVM did not crash at this point but a bit later because of the missing return statement.
    2) I replaced the code of the method in the native library with some testing code e.g. write something to a file. Then the crash happened again in this method.
    3) I copied the code of the method to a new project and run it directly from Netbeans. Everything was fine and it didn't crashed.
    I'm neither an expert in JNI nor in C++ but it seems to me that the crash happens if there is any code in this method!?

    Source Code:
    From the C++ source File:
    rcHeightfield* rcAllocHeightfield()
    {
     
             return 0;
    	rcHeightfield* hf = (rcHeightfield*)rcAlloc(sizeof(rcHeightfield), RC_ALLOC_PERM);
    	memset(hf, 0, sizeof(rcHeightfield));
    	return hf;
    }
    From the Wrapper made with SWIG:
    SWIGEXPORT jlong JNICALL Java_com_jme3_ai_navigation_utils_RecastJNI_rcAllocHeightfield(JNIEnv *jenv, jclass jcls) {
      jlong jresult = 0 ;
      rcHeightfield *result = 0 ;
     
      (void)jcls;
      result = (rcHeightfield *)rcAllocHeightfield();
      *(rcHeightfield **)&jresult = result;
      return jresult;
    }

    If you need any more source code just say it.

    I hope somebody can help me because I have no idea where to start.

    hololol2


  2. #2

    Default Re: JVM crashing on Method call

    I guess your Thread can already be attached to the VM, so AttachCurrentThread is not needed. Maybe you just need to check the thread state like this:

    How to obtain JNI interface pointer (JNIEnv *) for asynchronous calls

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