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2.你可以学历不高，你可以不上学，但你不能不学习
#include#include int i; void *pthread_proc_1(void *arg) { while(i<1000000) { i++; printf("%s %dn", __func__, i); sleep(5); } return NULL; } void *pthread_proc_2(void *arg) { while(i<1000000) { i++; printf("%s %dn", __func__, i); sleep(5); } return NULL; } void *pthread_proc_3(void *arg) { while(i<1000000) { i++; printf("%s %dn", __func__, i); sleep(5); } return NULL; } int main(void) { pthread_t thread1; pthread_create(&thread1, NULL, pthread_proc_1, NULL); pthread_t thread2; pthread_create(&thread2, NULL, pthread_proc_2, NULL); pthread_t thread3; pthread_create(&thread3, NULL, pthread_proc_3, NULL); sleep(500); return 0; } [点击并拖拽以移动]
代码不做分析
二、调试
主要目的熟悉多线程:
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
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Reading symbols from ./a.out...done.
（1）打断点在主函数中，断点必须是在创建线程完成后。
(gdb) b pthread_test.c:57
Breakpoint 1 at 0x400872: file pthread_test.c, line 57.
(gdb) r
Starting program: /home/mrlee/test/test/test/test/test/a.out
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff77ef700 (LWP 74724)]
pthread_proc_1 1
[New Thread 0x7ffff6fee700 (LWP 74725)]
pthread_proc_2 2
[New Thread 0x7ffff67ed700 (LWP 74726)]
Thread 1 "a.out" hit Breakpoint 1, main () at pthread_test.c:57
warning: Source file is more recent than executable.
57 sleep(500);
（2）查看线程数量与我们代码是否相同
(gdb) info threads
Id Target Id frame
* 1 Thread 0x7ffff7fd0700 (LWP 74720) "a.out" main () at pthread_test.c:57
2 Thread 0x7ffff77ef700 (LWP 74724) "a.out" 0x00007ffff78bc38d in nanosleep () at ../sysdeps/unix/syscall-template.S:84
3 Thread 0x7ffff6fee700 (LWP 74725) "a.out" 0x00007ffff78bc38d in nanosleep () at ../sysdeps/unix/syscall-template.S:84
4 Thread 0x7ffff67ed700 (LWP 74726) "a.out" clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:81
备注：*号表示现在对应的线程，前面的数字表示线程对应的id
（3）进入对应线程
(gdb) thread 2
[Switching to thread 2 (Thread 0x7ffff77ef700 (LWP 74724))]
#0 0x00007ffff78bc38d in nanosleep () at ../sysdeps/unix/syscall-template.S:84
84 ../sysdeps/unix/syscall-template.S: 没有那个文件或目录.
（4）锁定在此线程
(gdb) set scheduler-locking on
（5）查看此线程运行状态
(gdb) c
Continuing.
pthread_proc_1 3
pthread_proc_1 4
set sch pthread_proc_1 5
（6）解除线程锁定
(gdb) set scheduler-locking off
(gdb) c
Continuing.
pthread_proc_1 6
pthread_proc_3 7
pthread_proc_2 8
