Can i call multiple times JNI_CreateJavaVM? - c++

Question

I´m Trying to launch two threads witch calls "DispFrontEnd" function
First thread ended OK, second failed to start jvm.. ??
tks
#include "jni.h"
#include <process.h>
#include "Stdafx.h"
//DISPATCH Thread Check
bool DispatchThreadCreated = FALSE;
if (DispatchThreadCreated == FALSE)
{
HANDLE hDispThread;
hDispThread = (HANDLE)_beginthread(DispFrontEnd,0,(void *)dispatchInputs);
if ((long)hDispThread == -1)
{
log.LogError("Thread DispFrontEnd Returned********BG ", (long)hDispThread);
log.LogError("errno", errno);
log.LogError("_doserrno", _doserrno);
}
else
{
logloc->LogMethod("Dispatch Thread CREATED");
DispatchThreadCreated= TRUE;
//Espera que a thread termine
WaitForSingleObject( hDispThread, INFINITE );
DispatchThreadCreated= FALSE; // 01_02_2010
logloc->LogMethod("Dispatch Thread ENDED");
}
}
if (DispatchThreadCreated == FALSE)
{
HANDLE hDispThread3;
logloc->LogMethod("3 : Dispatch Thread CREATED");
hDispThread3 = (HANDLE)_beginthread(DispFrontEnd,0,(void *)dispatchInputs);
if ((long)hDispThread3 == -1)
{
log.LogError("3 : Thread DispFrontEnd Returned********BG ", (long)hDispThread3);
log.LogError("errno", errno);
log.LogError("_doserrno", _doserrno);
}
else
{
logloc->LogMethod("3 : Dispatch Thread CREATED");
DispatchThreadCreated= TRUE;
//Espera que a thread termine
WaitForSingleObject( hDispThread3, INFINITE );
DispatchThreadCreated= FALSE; // 01_02_2010
logloc->LogMethod("3 : Dispatch Thread ENDED");
}
}
void DispFrontEnd(void * indArr)
{
JNIEnv *env;
JavaVM *jvm;
env = create_vm(&jvm); // return null on second call ???
}
JNIEnv* create_vm(JavaVM ** jvm) {
CString str;
JNIEnv *env;
JavaVMInitArgs vm_args;
JavaVMOption options;
options.optionString = "-Djava.class.path=C:\\dispatch\\lib\\Run.jar;C:\\dispatch\\classes"; //Path to the java source code
vm_args.version = JNI_VERSION_1_6; //JDK version. This indicates version 1.6
vm_args.nOptions = 1;
vm_args.options = &options;
vm_args.ignoreUnrecognized = 0;
int ret = JNI_CreateJavaVM(jvm, (void**)&env, &vm_args);
if(ret < 0)
{
env = NULL;
str.Format("ERROR! create JVM (%d)",ret); // show this on second call!! ?
logloc->LogMethod( str );
}
else
{
str.Format("JVM %x created Success!",env->GetVersion());
logloc->LogMethod( str );
}
return env;
}

Answer 1

Do you really have to start many JVM ? Could you use
jint AttachCurrentThread(JavaVM *vm, JNIEnv **p_env, void *thr_args);
instead ?
The only thing I know is a native thread cannot attach two different JVM at the same time.