线程分离状态

分离状态的线程, 不能用pthread_join()等待它的终止状态.

例1:  修改属性, 创建分离状态线程

mypthread_attr_detach.c

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

//gcc -g mypthread_attr_detach.c -o mypthread_attr_detach -lpthread

#define ERROR(flag,msg)            \
if(flag)                        \
{                                \
    printf("%d: ",__LINE__);    \
    fflush(stdout);                \
    perror(msg);                \
    exit(errno);                \
}

void print(char *s)
{
    pid_t pid = getpid();
    pthread_t tid = pthread_self();
    printf("%s pid = %d,  tid = %lu(0x%lx)\n", s, pid, tid, tid);
}

void *thread_func(void *arg)
{
    int num;

    print("new thread");
    sleep(1);
    printf("%lu thread &num = 0x%lx\n", (unsigned long)arg, (unsigned long)&num);
    
    return arg;
}

#define MAX_THREAD 5

int main(int argc, char *argv[])
{
    int i;
    int size;
    pthread_t tid[MAX_THREAD];
    pthread_attr_t attr;

    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED);
    for(i = 0; i < MAX_THREAD; i++)
    {
        int ret = pthread_create(&tid[i], &attr,thread_func, (void *)(long)i);
        ERROR(ret != 0,"pthread_create()");
    }
    pthread_attr_destroy(&attr);
    
    print("main thread");
    
    int ret;
    int stat[MAX_THREAD];
    for(i = 0; i < MAX_THREAD; i++)
    {
        ret = pthread_join(tid[i], (void **)&stat[i]);
        if(ret != 0)
        {
            printf("pthread_join() fail!!! ");
        }
        printf("thread %lu(0x%lx) exit code = %d\n", tid[i], tid[i], stat[i]);
    }

    sleep(2);
    
    puts("byebye...");

    return 0;
}

编译链接运行, 输出如下:

对分离状态下的线程调用pthread_join()失败.

 

例2: 调用pthread_detach()使线程进入分离状态

mypthread_detach.c

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

//gcc -g mypthread_detach.c -o mypthread_detach -lpthread

#define ERROR(flag,msg)            \
if(flag)                        \
{                                \
    printf("%d: ",__LINE__);    \
    fflush(stdout);                \
    perror(msg);                \
    exit(errno);                \
}

void print(char *s)
{
    pid_t pid = getpid();
    pthread_t tid = pthread_self();
    printf("%s pid = %d,  tid = %lu(0x%lx)\n", s, pid, tid, tid);
}

void *thread_func(void *arg)
{
    int num;

    print("new thread");
    sleep(1);
    printf("%lu thread &num = 0x%lx\n", (unsigned long)arg, (unsigned long)&num);
    
    return arg;
}

#define MAX_THREAD 5

int main(int argc, char *argv[])
{
    int i;
    int size;
    pthread_t tid[MAX_THREAD];
    //pthread_attr_t attr;

    //pthread_attr_init(&attr);
    //pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED);
    for(i = 0; i < MAX_THREAD; i++)
    {
        //int ret = pthread_create(&tid[i], &attr,thread_func, (void *)(long)i);
        int ret = pthread_create(&tid[i], NULL, thread_func, (void *)(long)i);
        ERROR(ret != 0,"pthread_create()");

        pthread_detach(tid[i]);
    }
    //pthread_attr_destroy(&attr);
    
    print("main thread");
    
    int ret;
    int stat[MAX_THREAD];
    for(i = 0; i < MAX_THREAD; i++)
    {
        ret = pthread_join(tid[i], (void **)&stat[i]);
        if(ret != 0)
        {
            printf("pthread_join() fail!!! ");
        }
        printf("thread %lu(0x%lx) exit code = %d\n", tid[i], tid[i], stat[i]);
    }

    sleep(2);
    
    puts("byebye...");

    return 0;
}

编译链接执行, 输出如下:

对比将代码中的pthread_detach()注释掉后, 再编译链接执行, 输出如下: