C 语言多线程怎么读文件高效

C语言---多个线程读取文件，其代码如下：

#include

#include

#include

#include

#include

#include

#define THREAD_NUM 25

typedef struct

{undefined

FILE *_fp

int _nThreadId//第几个线程

sem_t *_semLock

}IDD_THREAD_PARAM

void *ThreadFunc(void *args)

{undefined

char sLine[100+1]

FILE *fpRead = ((IDD_THREAD_PARAM *)args)->_fp

sem_t *semLock = ((IDD_THREAD_PARAM *)args)->_semLock

int nId = ((IDD_THREAD_PARAM *)args)->_nThreadId

sem_wait(semLock)

while(!feof(fpRead))

{undefined

memset(sLine,0,sizeof(sLine))

fgets(sLine,100,fpRead)

fprintf(stderr,"Thread ID-%d:%s",nId,sLine)

}

sem_post(semLock)

}

int main()

{undefined

pthread_t *pThreads

sem_t semLock

pThreads = (pthread_t *)malloc(THREAD_NUM*sizeof(pthread_t))

sem_init(&semLock,0,1)

FILE *fp = fopen("test.txt","r")

//开始线程循环

IDD_THREAD_PARAM param

for(int i=0i

{undefined

memset(param,0,sizeof(IDD_THREAD_PARAM))

param._fp = fp

param._nThreadId = i

param._semLock = &semLock

pthread_create((pThreads+i),NULL,ThreadFunc,param)

}

for(int i=0i

pthread_join(*(pThreads+i),NULL)

free(pThreads)

pThreads = NULL

fclose(fp)

fp = NULL

return 0

}

生产者，消费者互斥同步参考如下代码：

#include <stdio.h>  

#include <stdlib.h>  

#include <unistd.h>  

#include <pthread.h>  

#include <errno.h>  

#include <error.h>  

#include <semaphore.h>  

  

#define PRODUCER_NUM 10  

#define CONSUMER_MUM 8  

#define BUFFER_SIZE 20  

#define SLEEP_TIME 1  

#define error_exit( _msg_ ) error(EXIT_FAILURE, errno, _msg_)  

  

int print()  

void *consumer_thread(void *args)  

void *producer_thread(void *args)  

  

sem_t can_produce  

sem_t can_consume  

pthread_mutex_t mutex  

int produce_index = 0  

int consume_index = 0  

int producer_id = 0  

int consumer_id = 0  

int buffer[BUFFER_SIZE] = {0}  

int main()  

{  

    int i  

    pthread_t producer[PRODUCER_NUM]  

    pthread_t consumer[CONSUMER_MUM]  

    int sinit1 = sem_init(&can_produce, 0, BUFFER_SIZE)  

    int sinit2 = sem_init(&can_consume, 0, 0)  

    if(sinit1 || sinit2)  

        error_exit("sem_init")  

    if(pthread_mutex_init(&mutex, NULL))  

        error_exit("pthread_mutex_init")  

    for(i=0 i<PRODUCER_NUM i++)  

        if(pthread_create(&producer[i], NULL, producer_thread, NULL))  

            error_exit("pthread_create")  

    for(i=0 i<CONSUMER_MUM i++)  

        if(pthread_create(&consumer[i], NULL, consumer_thread, NULL))  

            error_exit("pthread_create")  

    for(i=0 i<PRODUCER_NUM i++)  

        pthread_join(producer[i], NULL)  

    for(i=0 i<CONSUMER_MUM i++)  

        pthread_join(consumer[i], NULL)  

}  

void *producer_thread(void *args)  

{  

    int id = producer_id++  

    while(1){  

        sleep(SLEEP_TIME)  

        pthread_mutex_lock(&mutex)  

        sem_wait(&can_produce)  

        printf("Producer id %d in %d.\n", id, produce_index)  

        buffer[produce_index] = 1  

        produce_index = (produce_index + 1) % BUFFER_SIZE  

        print()  

        sem_post(&can_consume)  

        pthread_mutex_unlock(&mutex)  

    }  

    return NULL  

}  

void *consumer_thread(void *args)  

{  

    int id = consumer_id++  

    while(1){  

        sleep(SLEEP_TIME)  

        pthread_mutex_lock(&mutex)  

        sem_wait(&can_consume)  

        printf("Consumer id %d in %d.\n", id, consume_index)  

        buffer[consume_index] = 0  

        consume_index = (consume_index + 1) % BUFFER_SIZE  

        print()  

        sem_post(&can_produce)  

        pthread_mutex_unlock(&mutex)  

    }  

    return NULL  

}  

int print()  

{  

    int i  

    printf("Buffer:\n")  

    for(i = 0 i < BUFFER_SIZE i++)  

        printf("___")  

    printf("\n")  

    for(i = 0 i < BUFFER_SIZE i++)  

        printf("|%d|", buffer[i])  

    printf("\n")  

    for(i = 0 i < BUFFER_SIZE i++)  

        printf("___")  

    printf("\n")  

    return 0  

}

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