gdb调试死锁的正确姿势

gdb搞起

这是我们的源码：

#include <unistd.h> 
#include <pthread.h> 
#include <string.h> 
pthread_mutex_t lock_a = PTHREAD_MUTEX_INITIALIZER; 
pthread_mutex_t lock_b = PTHREAD_MUTEX_INITIALIZER;

/*!

我们构造一个死锁 ab ba

 */

void *  pthread_fun_1()
{
	while(1)
	{
		pthread_mutex_lock(&lock_a);
		pthread_mutex_lock(&lock_b);
		printf("-------%x\n",pthread_self());
		pthread_mutex_unlock(&lock_b);
		pthread_mutex_unlock(&lock_a);
	}
		return NULL;
}

void *  pthread_fun_2()
{
	while(1)
	{
		pthread_mutex_lock(&lock_b);
		pthread_mutex_lock(&lock_a);
		printf("-------%x\n",pthread_self());
		pthread_mutex_unlock(&lock_a);
		pthread_mutex_unlock(&lock_b);
	}  
		return NULL;

}
int main (void )
{

	pthread_t tid[2]={0};
	pthread_create(&tid[0], NULL, pthread_fun_1, NULL);
	pthread_create(&tid[1], NULL, pthread_fun_2, NULL);


	pthread_join(tid[0],NULL);
	pthread_join(tid[1],NULL);
	return 0;
}

gdb搞起。。。。。。。。

[email protected]:~$ pidof a.out 
9744
[email protected]:~$ sudo gdb attach 9744
[sudo] password for online: 
GNU gdb (Ubuntu 7.7-0ubuntu3) 7.7
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
attach: No such file or directory.
Attaching to process 9744
Reading symbols from /home/online/DeadLock/a.out...done.
Reading symbols from /lib/x86_64-linux-gnu/libpthread.so.0...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libpthread-2.19.so...done.
done.
[New LWP 9746]
[New LWP 9745]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Loaded symbols for /lib/x86_64-linux-gnu/libpthread.so.0
Reading symbols from /lib/x86_64-linux-gnu/libc.so.6...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libc-2.19.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/ld-2.19.so...done.
done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x00007fecccac165b in pthread_join (threadid=140655018829568, 
    thread_return=0x0) at pthread_join.c:92
92	pthread_join.c: No such file or directory.
(gdb) i thread
  Id   Target Id         Frame 
  3    Thread 0x7feccc6ee700 (LWP 9745) "a.out" __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
  2    Thread 0x7feccbeed700 (LWP 9746) "a.out" __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
* 1    Thread 0x7feccceda740 (LWP 9744) "a.out" 0x00007fecccac165b in pthread_join (threadid=140655018829568, thread_return=0x0) at pthread_join.c:92
(gdb) bt
#0  0x00007fecccac165b in pthread_join (threadid=140655018829568, 
    thread_return=0x0) at pthread_join.c:92
#1  0x000000000040088a in main () at dead_lock.c:47
(gdb) thread 2
[Switching to thread 2 (Thread 0x7feccbeed700 (LWP 9746))]
#0  __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
135	../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S: No such file or directory.
(gdb) bt
#0  __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
#1  0x00007fecccac2649 in _L_lock_909 ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
#2  0x00007fecccac2470 in __GI___pthread_mutex_lock (mutex=0x6010a0 <lock_a>)
    at ../nptl/pthread_mutex_lock.c:79
#3  0x00000000004007fa in pthread_fun_2 () at dead_lock.c:31
#4  0x00007fecccac0184 in start_thread (arg=0x7feccbeed700)
    at pthread_create.c:312
#5  0x00007feccc7ed03d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
(gdb) bt
#0  __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
#1  0x00007fecccac2649 in _L_lock_909 ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
#2  0x00007fecccac2470 in __GI___pthread_mutex_lock (mutex=0x6010a0 <lock_a>)
    at ../nptl/pthread_mutex_lock.c:79
#3  0x00000000004007fa in pthread_fun_2 () at dead_lock.c:31
#4  0x00007fecccac0184 in start_thread (arg=0x7feccbeed700)
    at pthread_create.c:312
#5  0x00007feccc7ed03d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
(gdb) l pthread_fun_2
22		}
23			return NULL;
24	}
25	
26	void *  pthread_fun_2()
27	{
28		while(1)
29		{
30			pthread_mutex_lock(&lock_b);
31			pthread_mutex_lock(&lock_a);
(gdb) p lock_aa
No symbol "lock_aa" in current context.
(gdb) 
No symbol "lock_aa" in current context.
(gdb) p lock_a
$1 = {__data = {__lock = 2, __count = 0, __owner = 9745, __nusers = 1, 
    __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, 
      __next = 0x0}}, 
  __size = "\002\000\000\000\000\000\000\000\021&\000\000\001", '\000' <repeats 26 times>, __align = 2}
(gdb) thread 3
[Switching to thread 3 (Thread 0x7feccc6ee700 (LWP 9745))]
#0  __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
135	../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S: No such file or directory.
(gdb) bt
#0  __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
#1  0x00007fecccac2649 in _L_lock_909 ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
#2  0x00007fecccac2470 in __GI___pthread_mutex_lock (mutex=0x6010e0 <lock_b>)
    at ../nptl/pthread_mutex_lock.c:79
#3  0x00000000004007b5 in pthread_fun_1 () at dead_lock.c:18
#4  0x00007fecccac0184 in start_thread (arg=0x7feccc6ee700)
    at pthread_create.c:312
#5  0x00007feccc7ed03d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
(gdb) l pthread_fun_1
9	
10	
11	 */
12	
13	void *  pthread_fun_1()
14	{
15		while(1)
16		{
17			pthread_mutex_lock(&lock_a);
18			pthread_mutex_lock(&lock_b);
(gdb) p lock_b
$2 = {__data = {__lock = 2, __count = 0, __owner = 9746, __nusers = 1, 
    __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, 
      __next = 0x0}}, 
  __size = "\002\000\000\000\000\000\000\000\022&\000\000\001", '\000' <repeats 26 times>, __align = 2}
(gdb) {__data = {__lock = 2, __count = 0, __owner = 9746, __nusers = 1, 
Undefined command: "".  Try "help".
(gdb)     __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, 
Undefined command: "__kind".  Try "help".
(gdb)       __next = 0x0}}, 
Undefined command: "__next".  Try "help".
(gdb)   __size = "\002\000\000\000\000\000\000\000\022&\000\000\001", '\000' <r

我们通过gdb可以清楚的看出：

线程1需要的锁的持有者是线程2

线程2需要的锁的持有者是线程1

gdb调试死锁的正确姿势

继续阅读

Linux操作系统：gcc编译器使用详解gcc如何完成重要概念：函数库

GCC/G++编译流程与编译选项程序的编译流程和编译选项

gcc cc c++ g++编译入门

C程序编译过程及常见选项--静态库和动态库前言一、gcc详讲二、静态库和动态库三、总结

gcc安装及使用GCC

gcc4.8.5升级到高版本gcc遇到的坑gcc4.8.5升级到高版本gcc遇到的坑

ubuntu 14 升级Gcc 5

Centos使用devtoolset安装gcc4.9.2

GDB调试指南：C++中如何调试生产环境的程序？GDB调试指南：C++中如何调试生产环境的程序？

mysqld的core文件1.产生core文件的条件2.产生core文件的位置3.如何使用core文件4.手动产生core文件

linux内核调试工具-addr2line和gdb定位问题

Clang Bug 43375 Mingw-w64 runtime failure: Unknown pseudo relocation protocol version 16777216解决方法

如何在Matlab 2016a中配置MinGW-w64 C/C++ 编译器

C/C++中多个库相互包含时，链接器的处理规则

.c文件编译过程（二进制可执行文件生成过程以及链接器）

嵌入式linux系统qt界面程序隐藏鼠标方法，踩坑过程分析