[置顶] Ｃ++ 实现线程池的精典模型
什么时候需要创建线程池呢？简单的说，如果一个应用需要频繁的创建和销毁线程，而任务执行的时间又非常短，这样线程创建和销毁的带来的开销就不容忽视，这时也是线程池该出场的机会了。如果线程创建和销毁时间相比任务执行时间可以忽略不计，则没有必要使用线程池了。
下面列出线程的一些重要的函数
int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void *(*start_routine) (void *), void *arg); void pthread_exit(void *retval); int pthread_mutex_destroy(pthread_mutex_t *mutex); int pthread_mutex_init(pthread_mutex_t *restrict mutex, const pthread_mutexattr_t *restrict attr); int pthread_mutex_lock(pthread_mutex_t *mutex); int pthread_mutex_trylock(pthread_mutex_t *mutex); int pthread_mutex_unlock(pthread_mutex_t *mutex); int pthread_cond_destroy(pthread_cond_t *cond); int pthread_cond_init(pthread_cond_t *restrict cond, const pthread_condattr_t *restrict attr); int pthread_cond_destroy(pthread_cond_t *cond); int pthread_cond_init(pthread_cond_t *restrict cond, const pthread_condattr_t *restrict attr); int pthread_cond_broadcast(pthread_cond_t *cond); int pthread_cond_signal(pthread_cond_t *cond);
下面是用Ｃ++实现线程池源码：
在该源码中，有两个文件，一个头文件pmutil.h, 一个源文件pmulti.cpp文件
下面是 pmuti.h 文件
#include <pthread.h>
typedef struct worker_node{ /*任务结点*/
void *(*process)(void *arg);
void *arg;
worker_node *next;
}worker_node;
typedef struct worker_queue{/*任务队列*/
private:
worker_node * head ,*tail ;
int cur_size ;
pthread_cond_t ready ;/**保持同步*/
pthread_mutex_t mutex ; /**保持互斥信号*/
bool destroy ;
public:
worker_queue();
~worker_queue();
int clean(); /*清空队列*/
int in_queue(const worker_node *node); /*任务入队*/
worker_node * out_queue(); /*任务出队*/
} worker_queue ;
class pmulti{
private:
pthread_t * threads ;
unsigned int thread_num;
mutable worker_queue * w_queue;
bool is_init;
bool is_destroy;
enum {QUEUE_MAX_SIZE=100};
public:
pmulti();
~pmulti();
int init(unsigned int num=10);
static void * thread_fun(void *arg); /*线程执行主函数*/
int add_worker(const worker_node * node); /*增加任务*/
int destroy();
};
pmulti.cpp文件
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>
#include "multi.h"
worker_queue::worker_queue():head(NULL),tail(NULL),cur_size(0),destroy(false){
pthread_mutex_init(&mutex,NULL);
pthread_cond_init(&ready,NULL);
}
worker_queue::~worker_queue(){
clean();
destroy = true ;
pthread_cond_broadcast(&ready);
pthread_mutex_destroy(&mutex);
pthread_cond_destroy(&ready);
}
int worker_queue::clean(){
worker_node* temp;
pthread_mutex_lock(&mutex);
while(NULL!=head){
temp = head ;
head = head->next ;
delete temp ;
}
tail=head=NULL;
cur_size = 0;
pthread_mutex_unlock(&mutex);
return 0;
}
int worker_queue::in_queue(const worker_node *node){
worker_node *temp;
temp = new worker_node ;
if(NULL == temp) return -1 ; //new err ;
*temp = *node ;
pthread_mutex_lock(&mutex);
if(NULL==head){
head=tail=temp;
}else{
tail->next=temp ;
tail = temp ;
tail->next = NULL;
}
cur_size++;
pthread_mutex_unlock(&mutex);
pthread_cond_signal(&ready);
return 0 ;
}
worker_node * worker_queue::out_queue(){ //out of the queue
pthread_mutex_lock(&mutex);
while((NULL==head) && (false == destroy)) { //queue empty
pthread_cond_wait(&ready,&mutex);
}
// assert(head!=NULL);
// assert(cur_size!=0);
if(destroy){
pthread_mutex_unlock(&mutex);
return NULL;
}
worker_node *temp;
temp = head ;
head = head->next ;
cur_size -- ;
pthread_mutex_unlock(&mutex);
return temp;
}
pmulti::pmulti():
is_init(false),thread_num(0),w_queue(NULL),threads(NULL),is_destroy(false){
}
pmulti::~pmulti(){
}
int pmulti::init(unsigned int thr_num){
if(is_init)
return -1;//alread init
int i;
//pool = new thread_pool;
//if(NULL == pool) return -2;//new error
//bzero(pool,sizeof(thread_pool));
w_queue = new worker_queue ;
if(NULL == w_queue) return -2;//new error
thread_num = thr_num;
threads = new pthread_t[thr_num] ;
for(i=0;i<thr_num;i++){
if(0!=pthread_create((threads+i),NULL,thread_fun,(void*)this ))
printf("pthread_create error\n");
}
is_destroy = false ;
is_init = true;
return 0;
}
int pmulti::add_worker(const worker_node * node){
return w_queue->in_queue(node);
}
int pmulti::destroy(){
int i=0;
char* res;
is_destroy = true ;
if(NULL != w_queue)
delete w_queue;
for(i=0;i<thread_num;i++){
pthread_join(threads[i],(void**)&res);
printf("joined :%lld end;\n",res);
}
if(thread_num > 0)
delete[] threads;
return 0;
}
void* pmulti::thread_fun(void*arg){
printf("thread num:%lld\n",pthread_self());
pmulti *pm =(pmulti*)arg;
worker_node * node ;
while(1){
if(pm->is_destroy)
pthread_exit(NULL);
node = pm->w_queue->out_queue();
if((NULL == node)|| (pm->is_destroy))
pthread_exit(NULL);
node->process(node->arg);
printf("thread_fun:%lld run\n",pthread_self());
}
return (void*)pthread_self();
}
void * test(void* i){
printf("test:%d\n",( int)i);
sleep(1);
return NULL;
}
int main(int argc,char ** args){
printf("this is main!\n");
class pmulti pm;
pm.init(15);
worker_node no ;
for(int i=0;i<5;i++){
no.process = &test ;
no.arg = (void*)(i*2);
pm.add_worker(&no);
}
sleep(5);
pm.destroy();
return 0;
}运行结果：
g++ multi.cpp multi.h -lpthread -o multi
[test@localhost multi_thread]$ ./multi
this is main!
thread num:24531909488
test:0
thread num:3046583152
test:2
thread num:3036093296
test:4
thread num:3025603440
test:6
thread num:3015113584
test:8
thread num:3004623728
thread num:3067562864
thread num:2994133872
thread num:2983644016
thread num:2973154160
thread num:2962664304
thread num:2952174448
thread num:2941684592
thread num:2931194736
thread num:3078052720
thread_fun:24531909488 run
thread_fun:3046583152 run
thread_fun:3036093296 run
thread_fun:3025603440 run
thread_fun:3015113584 run
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;
joined :0 end;