C ++程序JNI环境中的内存泄漏

Question

I have c++ program which in turn calls JAVA function ( which calls some API to get the result). The API which java is calling creating lot of memory to server request ( 1 GB memory for every 1000000 requests).

Can we free the memory from c/c++ program? or instruct the JVM to free the memory? It would be great help if you can help on this.

Thanks in advance...

Thanks Sambasiva.

Answer 1

Make explicit method that free all your resources in your C++ program

and try below code in your java class.

/******************************************************************************/
/*  File        : NativeCodeHandle.java                                       */
/*  Description : Blog-posting or Educational purpose                         */
/*  Written     : 2010.07.11                                                  */
/*  Version     : -_+                                                         */
/*  Author      : a.k.a LaZy Developer                                        */
/*  Contacts    : chriskr7@gmail.com                                          */
/******************************************************************************/

class someNativeClass{
  public native void allocateSomeMemory();
  public native void freeSomeMemory();
  static
  {
    System.loadLibrary("someSoDLLFile");
  }
}

public class NativeCodeHandle {

  boolean isCleaned = false;

  someNativeClass nativeObject = new someNativeClass();

  public synchronized void allocate(){
    nativeObject.allocateSomeMemory();
  }

  public synchronized void cleanup(){
    if(isCleaned) return;
    // free native code - maybe JNI free() wrapper method    
    nativeObject.freeSomeMemory();
    // maybe close DB connection
  }

  public void finalize(){
    cleanup();
    try {
      super.finalize();
    } catch (Throwable e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }    
  }
 /**
   * @param args
   */
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    NativeCodeHandle test = new NativeCodeHandle();
    test.allocate();
    // Explicit clean up!!! :P
    test.cleanup();
  }

}

Answer 2

There is nothing you can do unless you can modify your third party java class .

Also there are many risk if you call the third party java class more than once

if you force to free the resource from c++.