【操作系统】多线程和多进程的管理

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;

4000
}

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