编程范式15 笔记并行化

最新推荐文章于 2019-03-15 11:04:00 发布

原创最新推荐文章于 2019-03-15 11:04:00 发布 · 397 阅读

0 ·

CC 4.0 BY-SA版权

编程范式专栏收录该内容

23 篇文章

订阅专栏

本文介绍了一个基于并行计算的售票程序实现案例。通过对比串行与并行方式下的程序设计，展示了如何利用线程、共享内存及信号量来解决并发问题。介绍了基本的并行化策略和临界区管理方法。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

并行计算

假设有一个买票程序

int mian()
{
    int Agents=10;
    int Tickets=150;
    for(int i=1;i<=Agent;i++)
    {
        SellTicket(i,Agents,Tickets)
    }
}

void SellTickets(int i,int TicketsToSell)
{
    while(TicketsToSell>0){
        printf("%d sell a ticket\n",i)
        TicketsToSell--;
    }
    printf("all done\n");
}

并行化

int main()
{
    int Agents=10;
    int Tickets=150;
    InitThreadPackage(false);
    for(int i=1;i<=Agent;i++)
    {
        char name[32];
        sprintf(name,"%d sell thread",i);
        ThreadNew(name,SellTickets,2,i,Tickets/Agent);
    }
    RunAllThreads();
    return 0;
}

void SellTickets(int i,int TicketsToSell)
{
    while(TicketsToSell>0){
        printf("%d sell a ticket\n",i)
        TicketsToSell--;
        if(RandomChance(0.1))
            ThreadSleep(1000);
            //0.1的概率暂停占用CPU
            //不然还是按照顺序卖
    }
    printf("all done\n");
}

使用指针共享临界区

int main()
{
    int Agents=10;
    int Tickets=150;
    InitThreadPackage(false);
    for(int i=1;i<=Agent;i++)
    {
        char name[32];
        sprintf(name,"%d sell thread",i);
        ThreadNew(name,SellTickets,2,i,&Tickets/Agent);
    }
    RunAllThreads();
    return 0;
}

void SellTickets(int i,int *TicketsToSell)
{
    while(*TicketsToSell>0){
        printf("%d sell a ticket\n",i)
        *TicketsToSell--;
    }
    printf("all done\n");
}

信号量

int main()
{
    int Agents=10;
    int Tickets=150;
    Sempahore lock=SemaphoreNow(,1);
    InitThreadPackage(false);
    for(int i=1;i<=Agent;i++)
    {
        char name[32];
        sprintf(name,"%d sell thread",i);
        ThreadNew(name,SellTickets,2,i,&Tickets/Agent,lock);
    }
    RunAllThreads();
    return 0;
}

void SellTickets(int i,int *TicketsToSell)
{
    while(true)
    {
        SemaphoreWait(lock);
        if(*TicketsToSell==0) break;
`
    printf("%d sell a ticket\n",i)
        *TicketsToSell--;
        SemaphoreSignal(lock);
    }
    SemaphoreSignal(lock);
}