用Pthreads进程共享内存编程

更多的可以参考我的博客，也在陆续更新ing
http://www.hspweb.cn/

1、用VIM编写创建一个进程的代码，每隔一秒递增输出1-5。

#include 
#include 
void* fun(void* rank){
    int i;
    int my_rank=(int)rank;
    for(i=1;i<=5;i++){
        printf("Thread %d:%d\n",my_rank,i);
        sleep(1);
    }
    pthread_exit(0);
}
int main(){
  pthread_t tid1;   //the 2 thread identifier
  int num1=0;

  //create the thread
  pthread_create(&tid1,NULL,fun,(void *)num1);

  //now wait for the thread to exit
  pthread_join(tid1,NULL);
}

image

2、用VIM编写创建两个进程的代码，每隔一秒递增输出1-5。

#include 
#include 
void* fun(void* rank){
    int i;
    int my_rank=(int)rank;
    for(i=1;i<=5;i++){
        printf("Thread %d:%d\n",my_rank,i);
        sleep(1);
    }
    pthread_exit(0);
}
int main(){
  pthread_t tid1,tid2;  //the 2 thread identifier
  int num1=0,num2=1;

  //create the thread
  pthread_create(&tid1,NULL,fun,(void *)num1);
  pthread_create(&tid2,NULL,fun,(void *)num2);
  //now wait for the thread to exit
  pthread_join(tid1,NULL);
  pthread_join(tid2,NULL);
}

image

3、用VIM编写创建两个进程计算π的代码，观察竞争条件。

#include 
#include 
#include 
#include 
int n,thread_count;
double sum=0.0;

void* Thread_sum(void* rank){

    long my_rank=(long)rank;
    double factor;
    long long i;
    long long my_n=n/thread_count;
    long long my_first_i=my_n*my_rank;
    long long my_last_i=my_first_i+my_n;

    if(my_first_i % 2==0 ){
        factor=1.0;
    }else{
        factor=-1.0;
    }
    for(i=my_first_i;i

image

4、用忙等待互斥（严格轮换法）解决计算π的竞争条件。

#include 
#include 
#include 
#include 
#include "timer.h"
int n,thread_count;
double sum=0.0;
int flag=0;
void* Thread_sum(void* rank){
    long my_rank=(long)rank;
    double factor,my_sum=0.0;
    long long i;
    long long my_n=n/thread_count;
    long long my_first_i=my_n*my_rank;
    long long my_last_i=my_first_i+my_n;

    if(my_first_i % 2==0 ){
        factor=1.0;
    }else{
        factor=-1.0;
    }
    for(i=my_first_i;i

image

5、用Peterson解法解决计算π的竞争条件。

#include 
#include 
#include 
#include 
#include "timer.h"
int n,thread_count;
double sum=0.0;

int turn;
int interested[2];

void* Thread_sum(void* rank){
    long my_rank=(long)rank;
    double factor,my_sum=0.0;
    long long i;
    long long my_n=n/thread_count;
    long long my_first_i=my_n*my_rank;
    long long my_last_i=my_first_i+my_n;

    int other;
    other=(my_rank+1)%2;
    interested[my_rank]=1;

    if(my_first_i % 2==0 ){
        factor=1.0;
    }else{
        factor=-1.0;
    }
    for(i=my_first_i;i

image

6、用互斥量解决计算π的竞争条件。

#include 
#include 
#include 
#include 
#include "timer.h"
int n,thread_count;
double sum=0.0;
pthread_mutex_t mutex;

void* Thread_sum(void* rank){
    long my_rank=(long)rank;
    double factor,my_sum=0.0;
    long long i;
    long long my_n=n/thread_count;
    long long my_first_i=my_n*my_rank;
    long long my_last_i=my_first_i+my_n;

    if(my_first_i % 2==0 ){
        factor=1.0;
    }else{
        factor=-1.0;
    }
    for(i=my_first_i;i

image

7、用信号量实现互斥解决计算π的竞争条件。

#include 
#include 
#include 
#include 
#include 
#include "timer.h"
int n,thread_count;
double sum=0.0;

sem_t sem1,sem2;

void* Thread_sum(void* rank){
    long my_rank=(long)rank;
    double factor,my_sum=0.0;
    long long i;
    long long my_n=n/thread_count;
    long long my_first_i=my_n*my_rank;
    long long my_last_i=my_first_i+my_n;

    if(my_first_i % 2==0 ){
        factor=1.0;
    }else{
        factor=-1.0;
    }
    for(i=my_first_i;i

image

8、修改信号量的初值，调换上述2中的线程顺序。

#include 
#include 
#include 

sem_t sem1,sem2;
void* fun(void* rank){
    int i;
    int my_rank=(int)rank;
    for(i=1;i<=5;i++){
      if(my_rank==0)
        sem_wait(&sem1);
      else
        sem_wait(&sem2);
        printf("Thread %d:%d\n",my_rank,i);
        sleep(1);
      if(my_rank==0)
        sem_post(&sem2);
      else
        sem_post(&sem1);
    }
    pthread_exit(0);
}
int main(){
  pthread_t tid1,tid2;  //the 2 thread identifier
  int num1=0,num2=1;

  sem_init(&sem1,0,1);
  sem_init(&sem2,0,0);
  //create the thread
  pthread_create(&tid1,NULL,fun,(void *)num1);
  pthread_create(&tid2,NULL,fun,(void *)num2);
  //now wait for the thread to exit
  pthread_join(tid1,NULL);
  pthread_join(tid2,NULL);

  sem_destroy(&sem1);
  sem_destroy(&sem2);
}

image