Valgrind

About

Valgrind是一个用于构建动态分析工具的框架。Valgrind工具可以自动检测许多内存管理和线程错误，并详细分析你的程序。你也可以使用Valgrind构建新工具。

The Valgrind distribution currently includes seven production-quality tools: a memory error detector, two thread error detectors, a cache and branch-prediction profiler, a call-graph generating cache and branch-prediction profiler, and two different heap profilers. It also includes an experimental SimPoint basic block vector generator.

Valgrind’s Tool Suite

• Memcheck is a memory error detector. It helps you make your programs, particularly those written in C and C++, more correct.
• Cachegrind is a cache and branch-prediction profiler. It helps you make your programs run faster.
• Callgrind is a call-graph generating cache profiler. It has some overlap with Cachegrind, but also gathers some information that Cachegrind does not.
• Helgrind is a thread error detector. It helps you make your multi-threaded programs more correct.
• DRD is also a thread error detector. It is similar to Helgrind but uses different analysis techniques and so may find different problems.
• Massif is a heap profiler. It helps you make your programs use less memory.
• DHAT is a different kind of heap profiler. It helps you understand issues of block lifetimes, block utilisation, and layout inefficiencies.
• BBV is an experimental SimPoint basic block vector generator. It is useful to people doing computer architecture research and development.

GUI

• Valkyrie

ubuntu 安装

sudo apt-get install valgrind

valgrind --version
valgrind-3.18.1

编译程序

• 使用-g参数编译程序可以包含调试信息，这样可以在Memcheck的错误信息中包含准确的行号
• -O0 速度会慢些
• -O1 错误信息中的行号可能不准确，比-O0的速度快，但是运行Memcheck的效果相当好
• 不建议使用-O2及以上版本，因为Memcheck偶尔会报告不存在的未初始化值错误。

运行程序

myprog arg1 arg2

valgrind --leak-check=yes myprog arg1 arg2

• Memcheck是默认工具，--leak-check选项打开详细的内存泄漏检测器。

实例

一段有内存问题的C代码

#include <stdlib.h>

void f(void)
{
    int* x = malloc(10 * sizeof(int));
    x[10] = 0;        // problem 1: heap block overrun
}                    // problem 2: memory leak -- x not freed

int main(void)
{
    f();
    return 0;
}

## 编译
gcc -o example example.c -g

## 运行
valgrind --leak-check=yes ./example 1 2 

## 输出
==22116== Invalid write of size 4
==22116==    at 0x10916B: f (example.c:6)
==22116==    by 0x109180: main (example.c:11)
==22116==  Address 0x4a99068 is 0 bytes after a block of size 40 alloc'd
==22116==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==22116==    by 0x10915E: f (example.c:5)
==22116==    by 0x109180: main (example.c:11)

• 22116 : 进程ID，通常不重要
• Invalid write ： 错误类型