线程共享空间的代码验证
1.t1,t2两个线程共享空间:
参考代码:
#include <stdio.h>
#include <pthread.h>
//int pthread_create(pthread_t *restrict tidp, const pthread_attr_t *restrict attr, void *(*start_rtn)(void *), void *restrict arg);
// 返回:若成功返回0,否则返回错误编号----创建线程
void *func1(void*arg)//参数3:调用无类型指针API
{
printf("t1:%ld thread is create\n",(unsigned long)pthread_self());
//pthread_self():返回自身线程id,为pthread_t类型
printf("t1:param is %d:\n",*((int*)arg));//转化为int*,再取值
}
void *func2(void*arg)//参数3:调用无类型指针API
{
printf("t2:%ld thread is create\n",(unsigned long)pthread_self());
//pthread_self():返回自身线程id,为pthread_t类型
printf("t2:param is %d:\n",*((int*)arg));//转化为int*,再取值
}
int main()
{
int ret;//返回值
pthread_t t1;
pthread_t t2;
int param=100;//参数4:调用时:将int*转化为void*.100:随便给的数
ret=pthread_create(&t1,NULL,func1,(void*)¶m);
//参数1:指针指向t1,NULL:线程属性,参数3:启动线程调用的函数,参数4:打印的值
ret=pthread_create(&t2,NULL,func2,(void*)¶m);
if(ret==0)
{
printf("main函数创建线程t1成功\n");
}
if(ret==0)
{
printf("main函数创建线程t2成功\n");
}
printf("main:%ld\n",(unsigned long)pthread_self());
pthread_join(t1,NULL);//等待线程
pthread_join(t2,NULL);//等待线程
return 0;
}
结果显示:
dazai@dazai:~$ gcc demo2.c -lpthread
dazai@dazai:~$ ./a.out
main函数创建线程t1成功
main函数创建线程t2成功
main:-1210431744
t1:-1210434752 thread is create
t1:param is 100:
t2:-1218827456 thread is create
t2:param is 100:
注意:线程之间是竞争关系,每次运行顺序不一样
2.共享进程的使用:
main进程,t1进程,t2进程,相互竞争是g_data进行++操作:
参考代码:
#include <stdio.h>
#include <pthread.h>
//int pthread_create(pthread_t *restrict tidp, const pthread_attr_t *restrict attr, void *(*start_rtn)(void *), void *restrict arg);
// 返回:若成功返回0,否则返回错误编号----创建线程
int g_data =0;
void *func1(void*arg)//参数3:调用无类型指针API
{
printf("t1:%ld thread is create\n",(unsigned long)pthread_self());
//pthread_self():返回自身线程id,为pthread_t类型
printf("t1:param is %d:\n",*((int*)arg));//转化为int*,再取值
while(1)
{
printf("t1:%d\n",g_data++);
sleep(1);//打印一次睡眠一秒,保证公平分配CPU资源
}
}
void *func2(void*arg)//参数3:调用无类型指针API
{
printf("t2:%ld thread is create\n",(unsigned long)pthread_self());
//pthread_self():返回自身线程id,为pthread_t类型
printf("t2:param is %d:\n",*((int*)arg));//转化为int*,再取值
while(1)
{
printf("t2:%d\n",g_data++);
sleep(1);
}
}
int main()
{
int ret;//返回值
pthread_t t1;
pthread_t t2;
int param=100;//参数4:调用时:将int*转化为void*.100:随便给的数
ret=pthread_create(&t1,NULL,func1,(void*)¶m);
//参数1:指针指向t1,NULL:线程属性,参数3:启动线程调用的函数,参数4:打印的值
ret=pthread_create(&t2,NULL,func2,(void*)¶m);
if(ret==0)
{
printf("main函数创建线程t1成功\n");
}
if(ret==0)
{
printf("main函数创建线程t2成功\n");
}
printf("main:%ld\n",(unsigned long)pthread_self());
while(1)
{
printf("main:%d\n",g_data++);
sleep(1);//打印一次睡眠一秒,保证公平分配CPU资源
}
pthread_join(t1,NULL);//等待线程
pthread_join(t2,NULL);//等待线程
return 0;
}
执行结果:
dazai@dazai:~$ gcc demo2.c -lpthread
dazai@dazai:~$ ./a.out
main函数创建线程t1成功
main函数创建线程t2成功
main:-1210554624
main:0
t1:-1210557632 thread is create
t2:-1218950336 thread is create
t2:param is 100:
t2:1
t1:param is 100:
t1:2
t1:3
t2:3
main:4
t2:5
main:7
t1:6
t1:8
t2:9
main:10
main:11
t2:12
t1:13
main:14
t2:15
t1:16
.............................................
多个线程相互竞争
注意:如果在线程t1里面加入:
***if(g_data====3)
{
pthread_exit(NULL);
}***则线程t1不一定退出,想一想就能明白
解决方法:
见下一节线程4:线程同步之互斥量加锁解锁