【操作系统】多线程和多进程的管理

偏执的太偏执、 2023-10-17 17:32 56阅读 0赞

##### 一、实验目的 #####

> 加深对进程概念的理解，明确进程与线程的区别。  
> 掌握Linux进程创建和撤销的方法，进一步认识并发执行的实质。  
> 了解多线程的程序设计方法。

##### 二、实验项目内容 #####

> 多进程和多线程  
>  1号进程创建2，3号两个进程  
>  2号进程创建两个线程Thread1，Thread2  
>  Thread1：求（1~n）之间的素数  
>  Thread2：生成Fibonacci序列  
>  3号进程创建4，5号两个进程  
>  4号进程执行系统命令，ls，ps，cp等  
>  5号进程执行一个用户编写的可执行文件  
>  每个进程输出自己的进程ID和父进程的进程ID，观察分析，并画出程序的进程树结构。

##### 三、实验程序代码： #####

#include <stdio.h>
    #include <math.h>
    #include <sys/types.h>  
    #include <sys/wait.h>
    #include <unistd.h>
    #include <stdlib.h>
    #include <pthread.h>
    
    /**
    * Attention to add -lpthread and -lm when compile
    * eg : gcc process.c -lpthread -lm -o process
    */
    
    //The thread to find the prime number between (1~n)
    void *MyThread1(void* arg)
    {
        int n;
        //Get the resolve range
        printf("input the value of n:\n");
        scanf("%d",&n);
        printf("the prime number between 1~%d is:\n",n);
    
        for(int m=2;m<=n;m++)
        {
            if (m<=3)
            {
                printf("%4d",m);
                continue;  
            }
    
           int k=sqrt(m);  
           for(int i=2; i<=k; i++)
           {
                // printf("m: %f\n",k);
                if(m%i==0) 
                    break;  
                if(i>=k) 
                    printf("%4d",m);  
           }
        }
    
        printf("\n thread1 exit!\n");
        pthread_exit(0);
    }
    
    //The thread to generate Fibonacci sequences
    void *MyThread2(void* arg)
    {
        int fib0=0,fib1=1,fib2,i,N;
        printf("input fib value N:\n");
        scanf("%d",&N);
        printf("the fib sequences as following:\n");
        for (int i = 0; i < N; i++)
        {
            if (i==0)
            {
                printf("0");
            }
            else if (i==1)
            {
                printf("1");
            }
            else
            {
                fib2=fib0+fib1;
                printf("%d",fib2 );
                fib0=fib1;
                fib1=fib2;
            }
        }
        printf("\n thread2 exit!\n");
        pthread_exit(0);
    }
    
    //No.2 process create two threads
    int createThread()
    {
        int ret1=0,ret2=0;
        //Define the id of thread
        pthread_t id1,id2;
        //Create thread1
        ret1=pthread_create(&id1,NULL,MyThread1,NULL);
        if (ret1)
        {
            printf("Create pthread error!\n");
            return 1;
        }
        //Create thread2
        ret2=pthread_create(&id2,NULL,MyThread2,NULL);
        if (ret2)
        {
            printf("Create pthread error\n");
            return 1;
        }
    
        //Mainthread wait for childthread
        pthread_join(id1,NULL);
        pthread_join(id2,NULL);
    
        printf("main thread exit!\n");
        return 0;
    }
    
    //The Function of N0.4 and No.5
    void childProcessfunc(int i)
    {
        switch(i)
        {
            case 4:
                printf("\nThis is NO.4 process, ID is  %d, parent ID is %d, will create 2 thread\n",getpid(),getppid());
                printf("\nExcute system command ls:\n");
                system("ls");
                printf("\nExcute system command ps:\n");
                system("ps");
                printf("\nExcute system command cp:\n");
                system("cp sayhello.c sayhello.cpp");
    
                break;
            case 5:
                printf("\nThis is NO.5 process, ID is  %d, parent ID is %d, will create 2 thread\n",getpid(),getppid());
                printf("\nCarray out executable program:\n");
                system("./sayhello");
                break;
        }
        exit(0);
    }
    
    //No.3 process create two child process, N0.4 and No.5
    int createProcess()
    {
        int i;
        for (int i = 4; i <= 6; i++)
        {
            pid_t child=fork();
            //create process failed
            if (child==-1)    
            {
                printf("Error hanppened in fork function!\n");
                return 0;
            }
            //exert function when success
            else if(child==0)
            {
                childProcessfunc(i);
            }
        }
    
        for (int i = 0; i < 2; i++)
        {
            //Parent process waits child process
            pid_t tempPid=wait(NULL);
            printf("The process %d exit\n", tempPid);
        }
    
        return 0;
    }
    
    //The Function of N0.2 and No.3
    void mainProcessfunc(int i)
    {
        switch(i)
        {
            case 2:
                printf("\nThis is NO.2 process, ID is  %d, parent ID is %d, will create 2 thread\n",getpid(),getppid());
                createThread();
                break;
            case 3:
                printf("\nThis is NO.3 process, ID is  %d, parent ID is %d, will create 2 thread\n",getpid(),getppid());
                createProcess();
                break;
        }
        exit(0);
    }
    
    int main()
    {
        int i;
        //Create two child process, No.2 and No.3
        for (int i = 2; i < 4; i++)
        {
            pid_t child=fork();
            if (child==-1)
            {
                printf("Error happened in fork function!\n");
                return 0;
            }
            else if(child==0)
            {
                // printf("process Id is %d:\n",getpid());
                mainProcessfunc(i);
            }
        }
        for (int i = 0; i < 2; i++)
        {
            //Parent process waits child process
            pid_t tempPid=wait(NULL);
            printf("\nThe process %d exit\n", tempPid);
        }
        //Root process exit
        printf("\nThe No.1 root process Id is %d exit\n",getpid());
    
        return 0;
    }

注：在编译命令中添加-lpthread和 -lm ，-lpthread是表示要连接到pthread的库是这里省略的lib，因为在求素数算法中使用math库中sqrt函数，需要用到math.h，则加上 -lm。

##### 四、实验结果 #####

![这里写图片描述][SouthEast]

[SouthEast]: https://img-blog.csdn.net/20171224140528047?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvYWRtaW5wZA==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast