多进程和多线程编程

1、多进程编程

#include<stdlib.h>
#include<sys/types.h>
#include<unistd.h>

intmain()
{
pid_tchild_pid;

/*创建一个子进程*/
child_pid=fork();
if(child_pid==0)
{
printf("childpid\n");
exit(0);
}
else
{
printf("fatherpid\n");
sleep(60);
}

return0;
}

2、多线程编程

#include<stdio.h>
#include<pthread.h>

structchar_print_params
{
charcharacter;
intcount;
};

void*char_print(void*parameters)
{
structchar_print_params*p=(structchar_print_params*)parameters;
inti;

for(i=0;i<p->count;i++)
{
fputc(p->character,stderr);
}

returnNULL;
}

intmain()
{
pthread_tthread1_id;
pthread_tthread2_id;
structchar_print_paramsthread1_args;
structchar_print_paramsthread2_args;

thread1_args.character='x';
thread1_args.count=3000;
pthread_create(&thread1_id,NULL,&char_print,&thread1_args);

thread2_args.character='o';
thread2_args.count=2000;
pthread_create(&thread2_id,NULL,&char_print,&thread2_args);

pthread_join(thread1_id,NULL);
pthread_join(thread2_id,NULL);

return0;
}

3、线程同步与互斥

1）、互斥

pthread_mutex_tmutex;
pthread_mutex_init(&mutex,NULL);

/*也可以用下面的方式初始化*/
pthread_mutex_tmutex=PTHREAD_MUTEX_INITIALIZER;

pthread_mutex_lock(&mutex);
/*互斥*/

thread_flag=value;

pthread_mutex_unlock(&mutex);

2）、条件变量

intthread_flag=0;
pthread_mutex_tmutex;
pthread_cond_tthread_flag_cv;\

voidinit_flag()
{
pthread_mutex_init(&mutex,NULL);
pthread_cond_init(&thread_flag_cv,NULL);
thread_flag=0;
}

void*thread_function(void*thread_flag)
{
while(1)
{
pthread_mutex_lock(&mutex);
while(thread_flag!=0)
{
pthread_cond_wait(&thread_flag_cv,&mutex);
}
pthread_mutex_unlock(&mutex);

do_work();
}

returnNULL;
}

voidset_thread_flag(intflag_value)
{
pthread_mutex_lock(&mutex);
thread_flag=flag_value;

pthread_cond_signal(&thread_flag_cv);
pthread_mutex_unlock(&mutex);
}