Posted on 2008-04-30 16:45
MichaelCao 閱讀(971)
評(píng)論(4) 編輯 收藏 引用 所屬分類:
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覺得昨天的思考似乎還是不怎么過癮,有些問題還不是很清楚.到底應(yīng)用方面兩個(gè)有什么區(qū)別呢?
自己學(xué)著別人小小的動(dòng)了下手.
先貼信號(hào)量的代碼.
#include<pthread.h>
#include<stdio.h>
#include<sys/time.h>
#define MAX 10
pthread_t thread[2];
pthread_mutex_t mut;
int number=0,i;
void * thread1()
{
printf("thread1: I'm thread 1 \n");
for(i =0;i<MAX ;i++)
{
printf("thread 1: number=%d \n",number);
pthread_mutex_lock(&mut);
number++;
pthread_mutex_unlock(&mut);
sleep(2);
}
printf("thread1: 主函數(shù)在等我完成任務(wù)嗎?\n");
pthread_exit(NULL);
}
void * thread2()
{
printf("thread2: I'm thread 2 \n");
for(i =0; i<MAX;i++)
{
printf("thread2 : number=%d\n",number);
pthread_mutex_lock(&mut);
number++;
pthread_mutex_unlock(&mut);
sleep(3);
}
printf("thread2 : 主函數(shù)在等我完成任務(wù)么?\n");
pthread_exit(NULL);
}
void thread_create(void)
{
/*創(chuàng)建線程*/
pthread_create(&thread[0],NULL,thread1,NULL);
printf("線程1被創(chuàng)建!\n");
pthread_create(&thread[1],NULL,thread2,NULL);
printf("線程2被創(chuàng)建!\n");
}
void thread_wait(void)
{
/*等待線程結(jié)束*/
pthread_join(thread[0],NULL);
printf("線程1已經(jīng)結(jié)束!\n");
pthread_join(thread[1],NULL);
printf("線程2已經(jīng)結(jié)束!\n");
}
int main()
{
/*用默認(rèn)屬性初始化互斥鎖*/
pthread_mutex_init(&mut,NULL);
printf("我是主函數(shù),我正在創(chuàng)建線程!\n");
thread_create();
printf("我是主函數(shù),我正在等待線程完成任務(wù)!\n");
thread_wait();
}
執(zhí)行的結(jié)果是:
我是主函數(shù),我正在創(chuàng)建線程!
thread1: I'm thread 1
thread 1: number=0
線程1被創(chuàng)建!
thread2: I'm thread 2
thread2 : number=1
線程2被創(chuàng)建!
我是主函數(shù),我正在等待線程完成任務(wù)!
thread 1: number=2
thread2 : number=3
thread 1: number=4
thread 1: number=5
thread2 : number=6
thread 1: number=7
thread2 : number=8
thread 1: number=9
thread2 : number=10
thread1: 主函數(shù)在等我完成任務(wù)嗎?
線程1已經(jīng)結(jié)束!
thread2 : 主函數(shù)在等我完成任務(wù)么?
線程2已經(jīng)結(jié)束!
重要:這個(gè)執(zhí)行的過程大概要10秒!!!!!!
而我們用自旋鎖,代碼:
/*
* time :2008.4.30
* author:will cao
* Email:sei_michael@126.com
* 探索自旋鎖與信號(hào)量的區(qū)別
*/
#include<pthread.h>
#include<stdio.h>
pthread_t thread[2];
pthread_spinlock_t lock ;
#define MAX 10
int number=0,i;
void * thread1()
{
printf ("thread 1 :I began to run !");
for(i=0;i<MAX;i++)
{
printf("thread 1 :number=%d \n",number);
pthread_spin_lock(&lock);
number++;
pthread_spin_unlock(&lock);
}
printf("ok ,I am over !\n");
pthread_exit(NULL);
}
void * thread2 ()
{
printf("thread2 : I start !!!\n");
for(i=0;i<MAX;i++)
{
printf("thread2 : number = %d \n",number);
pthread_spin_lock(&lock);
number++;
pthread_spin_unlock(&lock);
}
printf("thread 2: I am over!!!");
pthread_exit(NULL);
}
void thread_create(void)
{
/*create the threads */
pthread_create(&thread[0],NULL,thread1,NULL);
printf("create the thread 1\n ");
pthread_create(&thread[1],NULL,thread2,NULL);
printf("create the thread 2 \n");
}
void thread_wait(void )
{
/*wait for the thread to be over */
pthread_join(thread[0],NULL);
printf("the thread 1 is over !\n");
pthread_join(thread[1],NULL);
printf("the thread 2 is over ! \n");
}
int main()
{
/* init the spin lock */
pthread_spin_init(&lock,0);
printf("i am the main,and I am creating the threads ");
thread_create();
printf("i am the main,and I am wait for the thread to be over!");
thread_wait();
}
執(zhí)行結(jié)果為:
i am the main,and I am creating the threads thread 1 :I began to run !thread 1 :number=0
thread 1 :number=1
thread 1 :number=2
thread 1 :number=3
thread 1 :number=4
thread 1 :number=5
thread 1 :number=6
thread 1 :number=7
thread 1 :number=8
thread 1 :number=9
ok ,I am over !
create the thread 1
thread2 : I start !!!
create the thread 2
i am the main,and I am wait for the thread to be over!thread2 : number = 10
thread2 : number = 11
thread2 : number = 12
thread2 : number = 13
thread2 : number = 14
thread2 : number = 15
thread2 : number = 16
thread2 : number = 17
thread2 : number = 18
thread2 : number = 19
thread 2: I am over!!!the thread 1 is over !
the thread 2 is over !
執(zhí)行時(shí)間:我沒用系統(tǒng)調(diào)用,但肯定是用不了0.1秒的...
總結(jié):從表面上來看,很明顯的區(qū)別是當(dāng)我們用的是信號(hào)量的時(shí)候,這個(gè)時(shí)候是有調(diào)度的.因?yàn)閺倪\(yùn)行結(jié)果上來看,主線程在創(chuàng)建其他兩個(gè)線程后,其他線程開始運(yùn)行.并且主線程也在運(yùn)行.但怎么運(yùn)行這個(gè)是無法確定的,這是一個(gè)并發(fā)的過程.
當(dāng)使用自旋鎖后,這個(gè)就不一樣了.當(dāng)運(yùn)行到臨界區(qū)的時(shí)候,它是直接的過去,不是會(huì)產(chǎn)生一個(gè)等待,或者一個(gè)調(diào)度.
不知道編譯器是怎么編譯的.很想知道編譯后二進(jìn)制代碼有什么區(qū)別.但這個(gè)好像有點(diǎn)太難....不過我覺得從運(yùn)行結(jié)果上來看這么多,應(yīng)該差不多了.