javaw memory usage grows by the usage of native method
Hello!
I have a very simple jni - method, which puts a string into the java String field:
JNIEXPORTvoid JNICALL Java_de_getStr(JNIEnv *env, jobject obj){
jclassclazz = (*env)->GetObjectClass(env, obj);
char myStr[5] ="aaaa";
jobject aString = (*env)->NewStringUTF(env, myStr);
jfieldID jfid = (*env)->GetFieldID(env, clazz,"drg","Ljava/lang/String;");
(*env)->SetObjectField(env, obj, jfid, aString);
(*env)->ReleaseStringUTFChars(env, aString, myStr);
(*env)->DeleteLocalRef(env, aString);
}
In java I have the following class:
publicclass MyClass
{
String drg;
privatenativevoid getStr();
public String getDRG()
{
getStr();
return drg;
}
}
When the getDRG() - Method will be called in a loop of ca.1000000 times you can see that the memory usage of the javaw grows.
Do you have any idea? I have to process a very large ammount of such strings and it finally comes to the "C:/BUILD_AREA/jdk1.5.0_03/hotspot\src\share\vm\utilities\growableArray.cpp.
Out of swap space?" - error
Thank you for any help
[1715 byte] By [
RGAnna] at [2007-11-27 9:15:12]
# 5
I repeated your code with JSE 1.5.0_07, OS - MS Windows 2003, MS VC++ 6.0 and no memory growth.
Java Code:
public class MyClass {
static {
System.loadLibrary("JavaMemory");
}
String drg;
private native void getStr();
public String getDRG()
{
getStr();
return drg;
}
public static void main(String[] args) {
MyClass mc = new MyClass();
for(int i = 0; i < 1000000; i++)
mc.getDRG();
}
}
C++ Code:
MyClass.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class MyClass */
#ifndef _Included_MyClass
#define _Included_MyClass
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class:MyClass
* Method:getStr
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_MyClass_getStr
(JNIEnv *, jobject);
#ifdef __cplusplus
}
#endif
#endif
StdAfx.h
// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently, but
//are changed infrequently
//
#if !defined(AFX_STDAFX_H__33F99590_F1FD_4C7C_B29F_61A308202C74__INCLUDED_)
#define AFX_STDAFX_H__33F99590_F1FD_4C7C_B29F_61A308202C74__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
// Insert your headers here
#define WIN32_LEAN_AND_MEAN// Exclude rarely-used stuff from Windows headers
#include <windows.h>
// TODO: reference additional headers your program requires here
//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.
#endif // !defined(AFX_STDAFX_H__33F99590_F1FD_4C7C_B29F_61A308202C74__INCLUDED_)
JavaMemory.cpp
#include "stdafx.h"
#include "MyClass.h"
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
return TRUE;
}
JNIEXPORT void JNICALL Java_MyClass_getStr(JNIEnv *env, jobject obj){
jclass clazz = env->GetObjectClass(obj);
char myStr[5] = "aaaa";
jobject aString = env->NewStringUTF(myStr);
jfieldID jfid = env->GetFieldID(clazz, "drg", "Ljava/lang/String;");
env->SetObjectField(obj, jfid, aString);
env->DeleteLocalRef(aString);
env->DeleteLocalRef(clazz);
}
