子線程退出后，導(dǎo)致主線程退出？

在主線程的末尾，我有一段打印的代碼：

圖片描述

我執(zhí)行了代碼之后，有時(shí)候可以打印出結(jié)果，有時(shí)候卻不可以打印結(jié)果：
圖片描述

圖片描述

那么是否和我想的那樣，子線程退出會(huì)導(dǎo)致主線程退出？

（這個(gè)程序是一個(gè)壓力測(cè)試程序，bug有點(diǎn)多）

詳細(xì)代碼如下：

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>

#include <sys/param.h>
#include <rpc/types.h>
#include <getopt.h>
#include <strings.h>
#include <time.h>
#include <signal.h>

#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>

#include <pthread.h>

int request_nums = 1;
int already_request_nums = 0;
int clients_num = 1;
int thread_nums = 1;
int failed = 0;
int success = 0;

int benchtime = 1; // 默認(rèn)持續(xù)發(fā)起請(qǐng)求的時(shí)間
int timerexpired = 0; // 是否請(qǐng)求到指定的時(shí)間（1表示時(shí)間到，0表示沒(méi)到時(shí)間）
int start = 0; //開(kāi)始/關(guān)閉標(biāo)志

pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;

const int MAX_LINE = 2048;

const int port = 80;

// 請(qǐng)求行的最大長(zhǎng)度
const int request_size = 2048;
char request[request_size];

const int url_max_size = 100;
char url[url_max_size];

// 發(fā)起請(qǐng)求
void *bench(void *arg);
// 構(gòu)造請(qǐng)求行
void build_request(const char *url);
ssize_t readline(int fd, char *vptr, size_t maxlen);
// 返回已經(jīng)建立連接的套接字
int create_socket (const char *host);
// 設(shè)置非阻塞
void setnonblocking(int sock);

void timeover(int sig) {
    timerexpired = 1;
}

// 顯示錯(cuò)誤，并且結(jié)束進(jìn)程
void error_die( const char *sc ) {
    perror(sc);
    exit(1);
}

/*
作用：設(shè)置文件描述符的狀態(tài)為非阻塞的
參數(shù)1：需要修改狀態(tài)的文件描述符
*/
void setnonblocking(int sock) {
    int opts;
    opts=fcntl(sock, F_GETFL);

    if(opts<0) {
        error_die("fcntl(sock,GETFL)");
    }

    opts = opts | O_NONBLOCK;

    if(fcntl(sock, F_SETFL, opts)<0) {
        error_die("fcntl(sock,SETFL,opts)");
    }
}

void *bench(void *arg) {
    int req_len;
    int sockfd[clients_num];
    char buf[1024];

    req_len = strlen(request); // 請(qǐng)求行的長(zhǎng)度

    // 創(chuàng)建套接字
    for (int i = 0; i < clients_num; ++i) {
        sockfd[i] = create_socket(url);

        if(sockfd[i] < 0) { // 連接服務(wù)器失敗，所以算一次請(qǐng)求失敗
            pthread_mutex_lock(&lock);
            failed++;
            pthread_mutex_unlock(&lock);
            continue;
        }
    }

    while(!start) {};

    while(1) {
        if (timerexpired) { // 時(shí)間到了，說(shuō)明上一次線程在請(qǐng)求連接的過(guò)程中可能被打斷了，所以不算失敗
            if (failed > 0) {
                pthread_mutex_lock(&lock);
                --failed;
                pthread_mutex_unlock(&lock);
            }

            // pthread_exit((void*)0);
        }

        for (int i = 0; i < clients_num; ++i) {
            int n = write(sockfd[i], request, req_len);
            if(n < 0) { // 沒(méi)有一次發(fā)送完，也算做一次請(qǐng)求失敗
                pthread_mutex_lock(&lock);
                failed++;
                pthread_mutex_unlock(&lock);
                continue;
            }

            int m = read(sockfd[i], buf, 1024);
            // printf("%s\n", buf);
            memset(buf, '\0', 1024);

            if (m > 0) {
                pthread_mutex_lock(&lock);
                ++success;
                pthread_mutex_unlock(&lock);
            }
        }
    }

    for (int i = 0; i < clients_num; ++i) {
        close(sockfd[i]);
    }

    // pthread_exit((void*)0);
}

// 構(gòu)造請(qǐng)求頭
void build_request(const char *url) {
    bzero(request, request_size);

    strcpy(request, "GET");

    strcat(request, " ");

    strcat(request, "/");

    strcat(request, " ");

    strcat(request, "HTTP/1.1");

    strcat(request, "\n");

    strcat(request, "host: localhost");

    strcat(request, "\n\n");
}

/*readline函數(shù)實(shí)現(xiàn)*/
ssize_t readline(int fd, char *vptr, size_t maxlen) {
    ssize_t n, rc;
    char    c, *ptr;

    ptr = vptr;
    for (n = 1; n < maxlen; n++) {
        if ( (rc = read(fd, &c,1)) == 1) {
            *ptr++ = c;
            if (c == '\n')
                break;  /* newline is stored, like fgets() */
        } else if (rc == 0) {
            *ptr = 0;
            return(n - 1);  /* EOF, n - 1 bytes were read */
        } else
            return(-1);     /* error, errno set by read() */
    }

    *ptr = 0;   /* null terminate like fgets() */
    return(n);
}

int create_socket (const char *host) {
    /*聲明套接字和鏈接服務(wù)器地址*/
    int sockfd;
    struct sockaddr_in servaddr;

    /*(1) 創(chuàng)建套接字*/
    if((sockfd = socket(AF_INET , SOCK_STREAM , 0)) == -1) {
        error_die("socket error");
    }

    /*(2) 設(shè)置鏈接服務(wù)器地址結(jié)構(gòu)*/
    bzero(&servaddr , sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(port); // 默認(rèn)為8080端口

    if(inet_pton(AF_INET , host , &servaddr.sin_addr) < 0) {
        printf("inet_pton error for %s\n", host);
        exit(1);
    }

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) {
        return sockfd;
    }

    if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
        perror("連接服務(wù)器失敗");
        return -1;
    }

    return sockfd;
}

int main(int argc, char **argv) {
    int ch;
    pthread_attr_t attr;
    struct sigaction action;

    // 解析命令行
    while((ch = getopt(argc, argv, "n:c:p:u:")) != -1) {
        switch(ch) {
            case 'n': // 總的請(qǐng)求數(shù)
                request_nums = atoi(optarg);
                break;
            case 'c': // 模擬出的客戶端數(shù)目
                clients_num = atoi(optarg);
                break;
            case 'p': // 總的線程個(gè)數(shù)
                thread_nums = atoi(optarg);
                break;
            case 'u': // 目標(biāo)url
                strcpy(url, optarg);
                break;
        }
    }


    build_request(url); // 構(gòu)造請(qǐng)求行

    pthread_attr_init(&attr);
    //注冊(cè)信號(hào)處理函數(shù)
    action.sa_handler = timeover;
    sigemptyset(&action.sa_mask);
    action.sa_flags = 0;

    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

    pthread_t tid[thread_nums];

    for (int i = 0; i < thread_nums; ++i) {
        /*創(chuàng)建子線程來(lái)對(duì)服務(wù)器進(jìn)行連接*/
        if(pthread_create(&tid[i] , NULL , bench, NULL) == -1) {
            perror("pthread create error.\n");
            exit(1);
        }
    }

    if(sigaction(SIGALRM, &action, NULL) < 0 ) {
        error_die("sigaction:");
    }

    alarm(benchtime);
    start = 1; // 開(kāi)始

    printf("總的請(qǐng)求數(shù)%d\n", request_nums);
    printf("連接數(shù)%d\n", clients_num);
    printf("線程數(shù)目%d\n", thread_nums);

    while(!timerexpired);

    printf("失敗次數(shù)：%d\n", failed);
    printf("成功次數(shù)：%d\n", success);
    pthread_attr_destroy(&attr);

    return 0;
}

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