Question

我尝试获取进程所有线程的回溯。我写了一个测试程序：

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

int func_a(int *a)
{
    *a++;
    return 0;
}

void* test_thread(void* args)
{
    int a = 0;
    while(1) {
        func_a(&a);
        //sleep(1);
    }
    fprintf(stdout, "%d\n", a);
    return NULL;
}

int main(int argc, char **argv) 
{  
    pthread_t pid = 0;
    pthread_create(&pid, NULL, test_thread, NULL);
    pthread_create(&pid, NULL, test_thread, NULL);
    pthread_create(&pid, NULL, test_thread, NULL);
    pause();
    return 0;
}

然后我运行程序并执行 pidof ./1|xargs -n1 sudo gdb --batch -ex "thread apply all bt full" -p 我看到了回溯。（太多的输出我只是选择了一些

Thread 2 (Thread 0xb459db40 (LWP 25272)):
#0  func_a (a=0xb459d354) at 1.c:6
No locals.
#1  0x0804871f in test_thread (args=0x0) at 1.c:21
        a = 382337846
#2  0xb775bf72 in start_thread (arg=0xb459db40) at pthread_create.c:312
        __res = <optimized out>
        pd = 0xb459db40
        now = <optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {-1216946176, -1269179584, 4001536, -1269181400, -56721544, -1538858626}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}}
        not_first_call = <optimized out>
        pagesize_m1 = <optimized out>
        sp = <optimized out>
        freesize = <optimized out>
        __PRETTY_FUNCTION__ = "start_thread"
#3  0xb7691f8e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:129
No locals.

但是当我在test_thread函数中启用sleep语句时，它无法获取回溯。

Thread 3 (Thread 0xb4d29b40 (LWP 26045)):
#0  0xb7716cf9 in ?? ()
No symbol table info available.
#1  0x00000000 in ?? ()
No symbol table info available.

Thread 2 (Thread 0xb4528b40 (LWP 26046)):
#0  0xb7716cf9 in ?? ()
No symbol table info available.
#1  0x00000000 in ?? ()
No symbol table info available.

有人知道为什么吗

感谢@Employed Russian指出缺陷。环境如下：

gcc版本：4.8.4
gdb版本：7.7.1
编译命令：gcc -g 1.c -o 1 -lpthread -rdynamic
〜/ .gdbinit不存在

我使用ubuntu 14.04

为什么在线程运行睡眠后backtrace信息已损坏？

0 个答案: