JVMTI/JNI and JVMTI_ERROR_INVALID_ENVIRONMENT

From:

Yao Qi <qiyaoltc@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 10 May 2007 01:42:42 +0800

Message-ID:

<m36471j3l9.fsf@gmail.com>

I write a sample code to get some information via JVMTI, but error
JVMTI_ERROR_INVALID_ENVIRONMENT is always here.

HelloWorld.java,

class HelloWorld {
    private native void print();
    public static void main(String[] args) {
    new HelloWorld().print();
    }
}

libjvmtiagent.c,

.....
JNIEXPORT void JNICALL
Java_HelloWorld_print(JNIEnv *env, jobject obj)
{
  jvmtiError err;
  jint owned_monitor_count, res;
  jobject* owned_monitors_ptr;

/*
  JavaVM* jvm;
  res = (*env)->GetJavaVM(env, &jvm);
  res = (*jvm)->GetEnv(jvm, (void **) &jvmti, JVMTI_VERSION_1_0);

  if (res != JNI_OK || jvmti == NULL)
    {
      printf("ERROR: Unable to access JVMTI Version 1 (0x%x),"
         " is your J2SE a 1.5 or newer version?"
         " JNIEnv's GetEnv() returned %d\n",
         JVMTI_VERSION_1, res);

    }
*/

  err = (*jvmti)->GetOwnedMonitorInfo (env, NULL, &owned_monitor_count, &owned_monitors_ptr);
  check_jvmti_error(jvmti, err, "Cannot get owned monitor infor\n");

  printf ("owned monitors is %d\n", (int)owned_monitor_count);
  err = (*jvmti)->Deallocate (env, owned_monitors_ptr);
  check_jvmti_error(jvmti, err, "Cannot deallocate\n");

  return;
}

Agent_OnLoad has been implemented properly, however when I run my
program like this,

$ LD_LIBRARY_PATH=. java -agentlib:jvmtiagent HelloWorld
jvmti = 0x831a7a8Got VM init event
callbackVMInit: main thread
ERROR: JVMTI: 116(JVMTI_ERROR_INVALID_ENVIRONMENT): Cannot get owned monitor infor

owned monitors is -1309188692
ERROR: JVMTI: 116(JVMTI_ERROR_INVALID_ENVIRONMENT): Cannot deallocate

Got VM Death event
Agent_OnUnload

Even I remove these comments in Java_HelloWorld_print above, this error
does not go away.

I am a newibe in JNI, and googled JVMTI_ERROR_INVALID_ENVIRONMENT for a
long time without any useful results.
Could anyone here give me some help on this? Thanks in advance.

--
Yao Qi <qiyaoltc@gmail.com> GNU/Linux Developer
http://duewayqi.googlepages.com/

To give of yourself, you must first know yourself.