valgrind调试办法
用法:
valgrind [options] prog-and-args options: 罕用选项，实用于所有Valgrind工具
抉择调试器
-tool=<name> 最罕用的选项。运行valgrind中名为toolname的工具。默认memcheck。
- memcheck ------> 这是valgrind利用最宽泛的工具，一个重量级的内存查看器，可能发现开发中绝大多数内存谬误应用状况，比方：应用未初始化的内存，应用曾经开释了的内存，内存拜访越界等。
- callgrind ------> 它次要用来检查程序中函数调用过程中呈现的问题。
- cachegrind ------> 它次要用来检查程序中缓存应用呈现的问题。
- helgrind ------> 它次要用来查看多线程程序中呈现的竞争问题。
- massif ------> 它次要用来检查程序中堆栈应用中呈现的问题。
- extension ------> 能够利用core提供的性能，本人编写特定的内存调试工具
- -h –help 显示帮忙信息。
- -version 显示valgrind内核的版本，每个工具都有各自的版本。
- -q –quiet 宁静地运行，只打印错误信息。
- -v –verbose 更具体的信息, 减少谬误数统计。
- -trace-children=no|yes 跟踪子线程? [no]
- -track-fds=no|yes 跟踪关上的文件形容？[no]
- -time-stamp=no|yes 减少工夫戳到LOG信息? [no]
- -log-fd=<number> 输入LOG到描述符文件 [2=stderr]
- -log-file=<file> 将输入的信息写入到指定文件中
- -log-file-exactly=<file> 输入LOG信息到file
- -log-file-qualifier=<VAR> 获得环境变量的值来做为输入信息的文件名。 [none]
- -log-socket=ipaddr:port 输入LOG到socket，ipaddr:port
LOG信息输入
- -xml=yes 将信息以xml格局输入，只有memcheck可用
- -num-callers=<number> show <number> callers in stack traces [12]
- -error-limit=no|yes 如果太多谬误，则进行显示新谬误 [yes]
- -error-exitcode=<number> 如果发现错误则返回错误代码 [0=disable]
- -db-attach=no|yes 当呈现谬误，valgrind会主动启动调试器gdb。[no]
- -db-command=<command> 启动调试器的命令行选项[gdb -nw %f %p]
实用于Memcheck工具的相干选项：
- -leak-check=no|summary|full 要求对leak给出详细信息 [summary]
- -leak-resolution=low|med|high how much bt merging in leak check [low]
- -show-reachable=no|yes show reachable blocks in leak check? [no]
最罕用的命令格局：
valgrind --tool=memcheck --leak-check=full ./appcache检测示例
源码参考如下：
gprof_demo.c
#include <stdio.h>#include <stdlib.h>#define BUFF_SIZE 10000long table[BUFF_SIZE][BUFF_SIZE];long col[BUFF_SIZE];long row[BUFF_SIZE];void initTable(){ int i, j; for (i = 0; i < BUFF_SIZE; i++) for (j = 0; j < BUFF_SIZE; j++) table[i][j] = random();}void sumCol(){ int i, j; for (j = 0; j < BUFF_SIZE; j++) for (i = 0; i < BUFF_SIZE; i++) col[j] = table[i][j];}void sumRow() { int i, j; for (i = 0; i < BUFF_SIZE; i++) for (j=0; j < BUFF_SIZE; j++) row[i] = table[i][j];}void printResult(){ int i; printf(" RAW\tCol\n"); for (i = 0; i < BUFF_SIZE; i++) printf("%8ld\t%8ld\n", row[i], col[i]);}int main(){ printf("hello\n"); initTable(); sumRow(); sumCol(); printResult(); return 0;}应用valgrind运行如下：
$ valgrind --tool=callgrind ./gprof_demo==56533== Callgrind, a call-graph generating cache profiler==56533== Copyright (C) 2002-2015, and GNU GPL'd, by Josef Weidendorfer et al.==56533== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info==56533== Command: ./gprof_demo==56533====56533== For interactive control, run 'callgrind_control -h'.hello RAW Col1908609430 12029551351712047379 15060195911864115174 19807356211322828066 15440181461395062755 16819284421721671889 999389080...1792209575 4085301092123570486 2123570486==56533====56533== Events : Ir==56533== Collected : 8212408375==56533====56533== I refs: 8,212,408,375应用kcachegrind查看调用工夫耗费
kcachegrind callgrind.out.52835callgrind.out.52835替换为具体的生成后果
如图：
如上，某些时候，因为valgrind应用模仿的形式进行程序运行，因而并不能精确的统计性能信息。
内存透露检测示例
源码参考如下：
/* gcc mem_check.c -o mem_check -g -O0 */#include <stdio.h>#include <stdlib.h>void test(void){ int *buf = malloc(10 * sizeof(int)); buf[10] = 0x55;}int main(void){ test(); return 0;}执行后果如下：
$ valgrind --leak-check=yes ./mem_check==1984== Memcheck, a memory error detector==1984== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.==1984== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info==1984== Command: ./mem_check==1984====1984== Invalid write of size 4==1984== at 0x1086CE: test (mem_check.c:9)==1984== by 0x1086DF: main (mem_check.c:14)==1984== Address 0x522d068 is 0 bytes after a block of size 40 alloc'd==1984== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)==1984== by 0x1086C1: test (mem_check.c:8)==1984== by 0x1086DF: main (mem_check.c:14)==1984====1984====1984== HEAP SUMMARY:==1984== in use at exit: 40 bytes in 1 blocks==1984== total heap usage: 1 allocs, 0 frees, 40 bytes allocated==1984====1984== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1==1984== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)==1984== by 0x1086C1: test (mem_check.c:8)==1984== by 0x1086DF: main (mem_check.c:14)==1984====1984== LEAK SUMMARY:==1984== definitely lost: 40 bytes in 1 blocks==1984== indirectly lost: 0 bytes in 0 blocks==1984== possibly lost: 0 bytes in 0 blocks==1984== still reachable: 0 bytes in 0 blocks==1984== suppressed: 0 bytes in 0 blocks==1984====1984== For counts of detected and suppressed errors, rerun with: -v==1984== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)能够看到valgrind找到两个谬误：
- 第9行代码存在有效的写入数据即越界拜访；
- 内存透露，调配了40字节没有开释。
email: MingruiZhou@outlook.com