理解内存分配，测试程序崩溃

问题描述

我只是读完K＆安培; R，这是所有我认识的温度。我所有的编辑从Windows命令行下使用的MinGW做的，我也没有先进的调试方法知识（因此我下面第二个节目贫民窟调试的评论）。

I am just about finished reading K&R, and that is all the C that I know. All my compilation is done from Windows command line using MinGW, and I have no knowledge of advanced debugging methods (hence the "ghetto debug" comment in my 2nd program below).

我试图做一些小的测试计划，以帮助我更好地了解内存的分配工作。这些第一对夫妇的程序不使用malloc或免费的，我只是想看看内存是如何分配和取消分配函数的局部标准芯片。这个想法是，我看我的正在运行的进程RAM的使用，看其是否与我的理解相对应。对于低于这个第一个程序，它的工作如我所料。在 alloc_one_meg（）函数分配并初始化25万4字节的整数，但MB是只要函数返回取消分配。所以，如果我调用该函数100万倍成一排，我从来没有看到我的内存使用率去远高于1MB。而且，它的工作原理。

I am trying to make a few small test programs to help me better understand how memory allocation works. These first couple programs do not use malloc or free, I just wanted to see how memory is allocated and de-allocated for standard arrays local to a function. The idea is that I watch my running processes RAM usage to see if it corresponds with what I understand. For this first program below, it does work as I expected. The alloc_one_meg() function allocates and initializes 250,000 4-byte integers, but that MB is de-allocated as soon as the function returns. So if I call that function 1000000 times in a row, I should never see my RAM usage go much above 1MB. And, it works.

#include <stdio.h>
#include <stdlib.h>

void alloc_one_meg() {
    int megabyte[250000];
    int i;
    for (i=0; i<250000; i++) {
        megabyte[i] = rand();
    }
}

main()
{
    int i;
    for (i=0; i<1000000; i++) {
        alloc_one_meg();
    }
}

有关低于这个第二个方案，当时的想法是不允许的功能退出，具有相同的功能运行1000个拷贝一次，我完成递归。我的理论是，该方案将消耗1GB的RAM完成递归后取消分配这一切之前。但是，它不会让过去通过递归第二循环（见我的贫民区调试注释）。该计划以pretty无信息的（对我）消息（Windows弹出说的 _ 的_。exe文件遇到问题）崩溃。通常我总是可以得到的东西与我的贫民区调试方法底部...但它不是在这里工作。我难倒。这有什么code中的问题？谢谢！

For this second program below, the idea was to not allow the function to exit, to have 1000 copies of the same function running at once, which I accomplished with recursion. My theory was that the program would consume 1GB of RAM before it de-allocated it all after the recursion finished. However, it doesn't get past the 2nd loop through the recursion (see my ghetto debug comment). The program crashes with a pretty non-informative (to me) message (a Windows pop-up saying __.exe has encountered a problem). Usually I can always get to the bottom of things with my ghetto debug method... but it's not working here. I'm stumped. What is the problem with this code? Thanks!

#include <stdio.h>
#include <stdlib.h>

int j=0;

void alloc_one_meg() {
    int megabyte[250000];
    int i;
    for (i=0; i<250000; i++) {
        megabyte[i] = rand();
    }
    j++;
    printf("Loop %d\n", j); // ghetto debug
    if (j<1000) {
        alloc_one_meg();
    }
}

main()
{
    alloc_one_meg();
}

后续问题发布here.

推荐答案

您正在运行到一个堆栈溢出。

You're running into a stack overflow.

本地自动存储变量（如兆）分配堆栈，这限制了的空间量上。的malloc分配堆，它允许更大的分配。

Local automatic storage variables (such as megabyte) are allocated on the stack, which has limited amount of space. malloc allocates on the heap, which allows much larger allocations.

您可以在这里阅读更多：

You can read more here:

（我应该注意的是，C语言不指定内存分配 - 堆和栈的实现细节）

(I should note that the C language does not specify where memory is allocated - stack and heap are implementation details)

这篇关于理解内存分配，测试程序崩溃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！