调整大小时,`std :: vector`会抛出“错误分配”异常

时间:2014-02-19 16:08:53

标签: c++ java-native-interface stdvector bad-alloc

我在C ++ dll中有以下代码,我通过JNI调用:

std::vector<double> myVector;
myVector.resize(10000000, 0);

我得到一个“错误分配”异常,即使向量的最大大小应该大于10000000。

我应该使用什么工具来跟踪内存分配,以便找到任何内存泄漏?

如果确实没有内存泄漏,我怎样才能减少向量的占用空间以确保我有足够的空间?

1 个答案:

答案 0 :(得分:1)

我知道这可能是找出你的分配大小的最糟糕的解决方案。所以这里:

main.cpp中:

#include "jni.h"
#include <vector>
#include <iostream>

#if (_MSC_VER == 1800) || (__cplusplus >= 201103L)
    #include <thread>
    #include <chrono>
#elif _MSC_VER
    #include <windows.h>
#else
    #include <unistd.h>
#endif


extern "C" JNIEXPORT void Java_test_Test_Alloc(JNIEnv* env, jobject obj, jint max_size, jint increment_size)
{
    std::vector<double> vec;
    size_t isize = max_size / 4;
    size_t oldsize = isize;

    while(isize <= max_size)
    {
        try
        {
            vec.resize(isize, 0);
            oldsize = isize;
            isize += increment_size;
            std::cout<<"Allocated: "<<vec.size() * sizeof(double)<<" bytes.\n";
        }
        catch (std::bad_alloc &e)
        {
            std::cout<<"Failed to allocate: "<<isize * sizeof(double)<<" bytes.\n";
            std::cout<<"Approx. max size: "<<oldsize * sizeof(double)<<" bytes.\n";
            std::cout<<"Exception: "<<e.what()<< "\n";
            std::cout<<"Vector.Max_Size(): "<<vec.max_size()<< "\n";
            break;
        }

        #if (_MSC_VER == 1800) || (__cplusplus >= 201103L)
            std::this_thread::sleep_for(std::chrono::seconds(1));
        #elif _MSC_VER
            Sleep(1);
        #else
            sleep(1);
        #endif
    }
}

#if defined _WIN32 || defined _WIN64
#include <windows.h>

extern "C" __declspec(dllexport) bool __stdcall DllMain(HINSTANCE hinstDLL, unsigned fdwReason, void* lpvReserved)
{
    switch (fdwReason)
    {
        case DLL_PROCESS_ATTACH:
            break;

        case DLL_PROCESS_DETACH:
            break;
    }
    return true;
}
#endif

在Java方面(Test.java):

package test;

public class Test {

    static {
        System.loadLibrary("JNITest");
    }

    public static native void Alloc(int max_size, int increment_size);

    public static void main(String[] args) {
        Alloc(100000000, 50000);
    }

}

对我来说,它会打印出来:

Allocated: 200000000 bytes.
Allocated: 200400000 bytes.
Allocated: 200800000 bytes.
.
.
.
Allocated: 399600000 bytes.
Allocated: 400000000 bytes.
Failed to allocate: 400400000 bytes.
Approx. max size: 400000000 bytes.
Exception: std::bad_alloc
Vector.Max_Size(): 536870911

就像我说的那样..这是一种“猜测”你可以分配多少钱的坏方法,但在这种情况下,没有其他人发布任何东西所以我将把它留在这里你可以使用它如果你希望..