Memory Leaks in JNI Calls

[ootsoo]

Hi all,

The past few queries i wanted to convey this ,,.

Please tell me if u get some solution for this ....

Description :-

I am facing memory leak problem in the following JNI

calls.

FindClass ()

CallStaticObjectMethod ()

CallIntMethod ()

GetStaticMethodID ()

GetMethodID ()

JNI_CreateJavaVM ()

When i use the above mentioned JNI calls in my code then

memory leak occurrs and the memory consumption increases

continiously.

Below is the sample code that i used to confirm the memory

leak in the JNI calls.

#include <jni.h>

#include <windows.h>

#include <conio.h>

#define MAXPATH 1024

#define JRE_KEY "Software\\JavaSoft\\Java Runtime Environment"

#define JVM_DLL "jvm.dll"

#ifdef _WIN32

#define PATH_SEPARATOR ';'

#else /* UNIX */

#define PATH_SEPARATOR ':'

#endif

#define USER_CLASSPATH "." /* where Prog.class is */

typedef jint (JNICALL *CreateJavaVM_t)(JavaVM **pvm, void **env, void *args);

typedef jint (JNICALL *GetDefaultJavaVMInitArgs_t)(void *args);

typedef struct {

CreateJavaVM_t CreateJavaVM;

GetDefaultJavaVMInitArgs_t GetDefaultJavaVMInitArgs;

} InvocationFunctions;

jboolean

LoadJavaVM(const char *jvmpath, InvocationFunctions *ifn)

{

HINSTANCE handle;

/* Load the Java VM DLL */

if ((handle = LoadLibrary(jvmpath)) == 0) {

fprintf(stderr, "Error loading: %s\n", jvmpath);

return JNI_FALSE;

}

/* Now get the function addresses */

ifn->CreateJavaVM =

(CreateJavaVM_t)GetProcAddress(handle, "JNI_CreateJavaVM");

ifn->GetDefaultJavaVMInitArgs =

(GetDefaultJavaVMInitArgs_t)GetProcAddress(handle, "JNI_GetDefaultJavaVMInitArgs");

if (ifn->CreateJavaVM == 0 || ifn->GetDefaultJavaVMInitArgs == 0) {

fprintf(stderr, "Error: can't find JNI interfaces in: %s\n", jvmpath);

return JNI_FALSE;

}

return JNI_TRUE;

}

static jboolean

GetStringFromRegistry(HKEY key, const char *name, char *buf, jint bufsize)

{

DWORD type, size;

if (RegQueryValueEx(key, name, 0, &type, 0, &size) == 0

&& type == REG_SZ

&& (size < (unsigned int)bufsize)) {

if (RegQueryValueEx(key, name, 0, 0, (LPBYTE)buf, &size) == 0) {

return JNI_TRUE;

}

}

return JNI_FALSE;

}

static jboolean

GetPublicJREHome(char *buf, jint bufsize)

{

HKEY key, subkey;

char version[MAXPATH];

/* Find the current version of the JRE */

if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, JRE_KEY, 0, KEY_READ, &key) != 0) {

fprintf(stderr, "Error opening registry key '" JRE_KEY "'\n");

return JNI_FALSE;

}

if (!GetStringFromRegistry(key, "CurrentVersion",

version, sizeof(version))) {

fprintf(stderr, "Failed reading value of registry key:\n\t"

JRE_KEY "\\CurrentVersion\n");

RegCloseKey(key);

return JNI_FALSE;

}

/* Find directory where the current version is installed. */

if (RegOpenKeyEx(key, version, 0, KEY_READ, &subkey) != 0) {

fprintf(stderr, "Error opening registry key '"

JRE_KEY "\\%s'\n", version);

RegCloseKey(key);

return JNI_FALSE;

}

if (!GetStringFromRegistry(subkey, "JavaHome", buf, bufsize)) {

fprintf(stderr, "Failed reading value of registry key:\n\t"

JRE_KEY "\\%s\\JavaHome\n", version);

RegCloseKey(key);

RegCloseKey(subkey);

return JNI_FALSE;

}

RegCloseKey(key);

RegCloseKey(subkey);

return JNI_TRUE;

}

main() {

InvocationFunctions ifn;

JNIEnv *env;

JavaVM *jvm;

JavaVMInitArgs args;

JavaVMOption options[1];

jint res;

jobject obj;

jclass cls;

jmethodID mid;

char jvmpath[MAXPATH];

/* IMPORTANT: specify vm_args version # if you use JDK1.1.2 and beyond */

GetPublicJREHome(jvmpath,MAXPATH);

strcat(jvmpath,"\\bin\\client\\jvm.dll");

ifn.CreateJavaVM = 0; ifn.GetDefaultJavaVMInitArgs = 0;

LoadJavaVM(jvmpath, &ifn);

// Fill the args structure

args.version = JNI_VERSION_1_4;

args.nOptions = 1;

options[0].optionString = "-Djava.class.path=E:\\sample";

args.options = options;

args.ignoreUnrecognized = JNI_FALSE;

// Create the Java VM

//res = JNI_CreateJavaVM(&jvm,(void **)&env,&args);

res = (*ifn.CreateJavaVM)(&jvm,(void **)&env,&args);

if (res < 0) {

fprintf(stderr, "Can't create Java VM\n");

exit(1);

}

// Find the User defined class

cls = env->FindClass("HelloWorld");

if (cls == 0) {

res=GetLastError();

fprintf(stderr, "Can't find Hello World class\n");

exit(1);

}

int i=0;

while(1)

{

// Get the Method Id to be invoked

mid = env->GetMethodID(cls, "sample", "()V");

if (mid == 0) {

return 1;

}

// Creation of New Object and Execution of Method

obj = env->NewObject(cls,mid);

i++;

// Calling the Method using the object

env->CallVoidMethod(obj, mid);

//mid =NULL;

// Get the static method ID

mid = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");

if (mid == 0) {

fprintf(stderr, "Can't find Prog.main\n");

exit(1);

}

// Invoking the main function call

env->CallStaticVoidMethod(cls, mid);

//mid =NULL;

// Creation of new object

jobject obj1 = env->AllocObject(cls);

// Get the Method Id to be invoked

mid = env->GetMethodID(cls,"sum","(II)I");

jint result;

// Invoking the method using parameters

//while(i<=500)

//{

result = env->CallIntMethod(obj1,mid,2,6);

i++;

//}

//mid =NULL;

printf("\nResult is %d",result);

// Invoking the Constructor

mid = env->GetMethodID(cls,"<init>","(I)V");

env->CallVoidMethod(obj1,mid,4);

//mid =NULL;

mid = env->GetMethodID(cls,"getVar","()I");

jint r2 = env->CallIntMethod(obj1,mid);

//mid =NULL;

// Deletion of objects

env->DeleteLocalRef(obj);

env->DeleteLocalRef(obj1);

}

jvm->DestroyJavaVM();

getch();

}

thanks & regards,

Ootsoo