互斥量解决生产者-消费者问题

用互斥量解决生产中-消费者问题
当生产者的生产速度低于消费者的消费速度时，消费者必须等待，所以就会产生多次不必的锁资源申请释放动作。影响系统性能。

#include<pthread.h>#include<stdio.h>#include<stdlib.h>#include<unistd.h>pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;typedef struct _Node{    int val;    struct _Node* next;}Node;typedef struct _Args{    Node* head;}Args;Node* head;void Init(){    head=NULL;}void PushBack(int val){    Node* node=(Node*)malloc(sizeof(Node));    node->val=val;    node->next=NULL;    if(head==NULL)    {        head=node;        return;    }    Node* temp=head;    while(temp->next!=NULL)    {        temp=temp->next;    }    temp->next=node;    }int PopFront(){    if(head==NULL)    {        printf("list is empty\n");        return -1;    }    Node* temp=head;    head=(head)->next;    int res=temp->val;    free(temp);    return res;}void PrintList(){    Node* temp=head;    while(temp!=NULL)    {        printf("%4d",temp->val);        temp=temp->next;    }    printf("\n");}void* Consumer(void* args){    for(int i=0;i<10;i++)    {    pthread_mutex_lock(&mutex);        int res=PopFront();    if(res!=-1)    {         printf("In consumer:[%d]\n",res);        }    pthread_mutex_unlock(&mutex);    sleep(1);    }}void* Producter(void* args){        for(int i=0;i<10;i++)    {        pthread_mutex_lock(&mutex);    PushBack(i);    printf("In Producter:[%d]\n",i);    pthread_mutex_unlock(&mutex);    sleep(2);    }}int main(){    Init(&head);    Args args;    args.head=head;    pthread_t pid[2];    pthread_create(&pid[0],NULL,Producter,(void*)&args);    pthread_create(&pid[1],NULL,Consumer,(void*)&args);        pthread_join(pid[0],NULL);    pthread_join(pid[1],NULL);    pthread_mutex_destroy(&mutex);    return 0;}

结果如下

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添加条件变量之后
把模型改为最多只能保留5个东西，

#include<pthread.h>#include<stdio.h>#include<stdlib.h>#include<unistd.h>pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;pthread_cond_t condp=PTHREAD_COND_INITIALIZER;pthread_cond_t condc=PTHREAD_COND_INITIALIZER;#define MAXLEN 5typedef struct _Node{    int val;    struct _Node* next;}Node;typedef struct _Args{    Node* head;}Args;Node* head;int size;void Init(){    head=NULL;    size=0;}void PushBack(int val){    Node* node=(Node*)malloc(sizeof(Node));    node->val=val;    node->next=NULL;    if(head==NULL)    {        head=node;        return;    }    Node* temp=head;    while(temp->next!=NULL)    {        temp=temp->next;    }    temp->next=node;    size++;    }int PopFront(){    if(head==NULL)    {        printf("list is empty\n");        return -1;    }    Node* temp=head;    head=(head)->next;    int res=temp->val;    free(temp);    size--;    return res;}void PrintList(){    Node* temp=head;    while(temp!=NULL)    {        printf("%4d",temp->val);        temp=temp->next;    }    printf("\n");}void* Consumer(void* args){    while(1)    {    pthread_mutex_lock(&mutex);    while(size==0)    {         pthread_cond_wait(&condc,&mutex);    }   int res= PopFront();    if(size<MAXLEN)    {        pthread_cond_signal(&condp);    }    printf("In consumer:[%d]\n",res);         pthread_mutex_unlock(&mutex);    sleep(3);    }}void* Producter(void* args){        while(1)    {        pthread_mutex_lock(&mutex);    while(size==MAXLEN)    {        pthread_cond_wait(&condp,&mutex);    }    int i=rand()%1000;    PushBack(i);    printf("size = %d\n",size);    if(size>0)    {        pthread_cond_signal(&condc);    }    printf("In Producter:[%d]\n",i);    pthread_mutex_unlock(&mutex);    sleep(1);    }}int main(){    Init(&head);    Args args;    args.head=head;    pthread_t pid[2];    pthread_create(&pid[1],NULL,Consumer,(void*)&args);     pthread_create(&pid[0],NULL,Producter,(void*)&args);           pthread_join(pid[0],NULL);    pthread_join(pid[1],NULL);    pthread_mutex_destroy(&mutex);    pthread_cond_destroy(&condp);    pthread_cond_destroy(&condc);    return 0;}

结果如图