new不分配内存 [英] new does not allocate memory

问题描述

这应该填充我的记忆每秒用ca 100 MB。我用gnome-systemmonitor和htop跟踪内存消耗。但不知何故，它不。为什么？

  #includeunistd.h
 #include< iostream& 
 
 int main（int argc，char * argv []）
 {
 while（true）{
 std :: cout< 新一个< std :: endl; 
 new char [100000000]; 
 sleep（1）; 
} 
 return 0; 
} 
  

运行：

  g ++ -std = c ++ 11 -O0 main.cpp; ./a.out 
  

解决方案

如果你放了一些代码，如：

。如果你不使用它，那么它就不会映射任何内存页。

  char * test = new char [100000000] 
 test [0] ='a'; 
 test [4096] ='b'; 
 ... 
  

您应该看到它实际上消耗了您的系统内存。

This should fill my memory every second with ca 100 MB. I track the memoryusage with gnome-systemmonitor and htop. But somehow it does not. Why?

#include "unistd.h"
#include <iostream>

int main(int argc, char *argv[])
{
    while (true){
        std::cout << "New one" << std::endl;
        new char[100000000];
        sleep(1);
    }
    return 0;
}

To run:

g++ -std=c++11 -O0  main.cpp; ./a.out  

解决方案

Because you're not using it, Linux does lazy allocation so it will not actually map any memory page until you use it.

If you put some code like:

char* test = new char[100000000];
test[0] = 'a';
test[4096] = 'b';
...

You should see it's actually consuming your system memory.

这篇关于new不分配内存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IT屋！