Webbench源码分析

Webbench是Linux下的一个网站压力测试工具， 由C实现。其展示两项数据： 每秒钟响应请求数和每秒钟传输数据量。 官网地址：home.tiscali.cz/~cz210552/w…

Webbench使用示例

1. 下载 wget home.tiscali.cz/~cz210552/d…
2. 解压缩 tar zxvf webbench-1.5.tar.gz
3. 安装 make & make install
4. 压测 webbench -c 30 -t 20 www.baidu.com。`-c`表示并行客户端进程数量，`-t`表示压测时间，单位秒。
5. 具体提供的参数如下

            "webbench [option]... URL\n"
            "  -f|--force               Don't wait for reply from server.\n"
            "  -r|--reload              Send reload request - Pragma: no-cache.\n"
            "  -t|--time <sec>          Run benchmark for <sec> seconds. Default 30.\n"
            "  -p|--proxy <server:port> Use proxy server for request.\n"
            "  -c|--clients <n>         Run <n> HTTP clients at once. Default one.\n"
            "  -9|--http09              Use HTTP/0.9 style requests.\n"
            "  -1|--http10              Use HTTP/1.0 protocol.\n"
            "  -2|--http11              Use HTTP/1.1 protocol.\n"
            "  --get                    Use GET request method.\n"
            "  --head                   Use HEAD request method.\n"
            "  --options                Use OPTIONS request method.\n"
            "  --trace                  Use TRACE request method.\n"
            "  -?|-h|--help             This information.\n"
            "  -V|--version             Display program version.\n"

Webbench源码

主要包括两个文件，socket.c和webbench.c，总行数约550行。

1. webbench用多进程的方式，模拟多客户端并行访问服务器。

// webbench.c
    /* fork childs */
    for(i=0;i<clients;i++)
    {
        pid=fork();
        if(pid <= (pid_t) 0)
        {
            /* child process or error*/
            sleep(1); /* make childs faster */
            break;
        }
    }

2. 用pipe管道，实现子进程和主进程的通信。

// webbench.c
    /* 创建管道 */
    if(pipe(mypipe))
    {
        perror("pipe failed.");
        return 3;
    }

3. 子进程向WebServer发起请求，并把结果写入管道

     nexttry:while(1)
    {
        if(timerexpired)
        {
            if(failed>0)
            {
                /* fprintf(stderr,"Correcting failed by signal\n"); */
                failed--;
            }
            return;
        }
        
        s=Socket(host,port);                          
        if(s<0) { failed++;continue;} 
        if(rlen!=write(s,req,rlen)) {failed++;close(s);continue;}
        if(http10==0) 
        if(shutdown(s,1)) { failed++;close(s);continue;}
        if(force==0) 
        {
            /* read all available data from socket */
            while(1)
            {
                if(timerexpired) break; 
                i=read(s,buf,1500);
                /* fprintf(stderr,"%d\n",i); */
                if(i<0) 
                { 
                    failed++;
                    close(s);
                    goto nexttry;
                }
                else
                if(i==0) break;
                else
                bytes+=i;
            }
        }
        if(close(s)) {failed++;continue;}
        speed++;
    }

4. 父进程读取子进程的数据，并汇总

        while(1)
        {
            pid=fscanf(f,"%d %d %d",&i,&j,&k);
            if(pid<2)
            {
                fprintf(stderr,"Some of our childrens died.\n");
                break;
            }
            
            speed+=i;
            failed+=j;
            bytes+=k;
        
            /* fprintf(stderr,"*Knock* %d %d read=%d\n",speed,failed,pid); */
            if(--clients==0) break;
        }
    
        fclose(f);

        printf("\nSpeed=%d pages/min, %d bytes/sec.\nRequests: %d susceed, %d failed.\n",
            (int)((speed+failed)/(benchtime/60.0f)),
            (int)(bytes/(float)benchtime),
            speed,
            failed);

5. socket.c负责向连接WebServer

int Socket(const char *host, int clientPort)
{
    int sock;
    unsigned long inaddr;
    struct sockaddr_in ad;
    struct hostent *hp;
    
    memset(&ad, 0, sizeof(ad));
    ad.sin_family = AF_INET;

    inaddr = inet_addr(host);
    if (inaddr != INADDR_NONE)
        memcpy(&ad.sin_addr, &inaddr, sizeof(inaddr));
    else
    {
        hp = gethostbyname(host);
        if (hp == NULL)
            return -1;
        memcpy(&ad.sin_addr, hp->h_addr, hp->h_length);
    }
    ad.sin_port = htons(clientPort);
    
    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock < 0)
        return sock;
    if (connect(sock, (struct sockaddr *)&ad, sizeof(ad)) < 0)
        return -1;
    return sock;
}