我写了一个简单的多线程C程序来访问MySQL,它工作正常,除了,当我在每个线程函数中添加usleep()或sleep()函数。 我创建在主方法二并行线程,多线程访问MySQL错误
int main(){
mysql_library_init(0,NULL,NULL);
printf("Hello world!\n");
init_pool(&p,100);
pthread_t producer;
pthread_t consumer_1;
pthread_t consumer_2;
pthread_create(&producer,NULL,produce_fun,NULL);
pthread_create(&consumer_1,NULL,consume_fun,NULL);
pthread_create(&consumer_2,NULL,consume_fun,NULL);
mysql_library_end();
}
void * produce_fun(void *arg){
pthread_detach(pthread_self());
//procedure
while(1){
usleep(500000);
printf("producer...\n");
produce(&p,cnt++);
}
pthread_exit(NULL);
}
void * consume_fun(void *arg){
pthread_detach(pthread_self());
MYSQL db;
MYSQL *ptr_db=mysql_init(&db);
mysql_real_connect();
//procedure
while(1){
usleep(1000000);
printf("consumer...");
int item=consume(&p);
addRecord_d(ptr_db,"test",item);
}
mysql_thread_end();
pthread_exit(NULL);
}
void addRecord_d(MYSQL *ptr_db,const char *t_name,int item){
char query_buffer[100];
sprintf(query_buffer,"insert into %s values(0,%d)",t_name,item);
//pthread_mutex_lock(&db_t_lock);
int ret=mysql_query(ptr_db,query_buffer);
if(ret){
fprintf(stderr,"%s%s\n","cannot add record to ",t_name);
return;
}
unsigned long long update_id=mysql_insert_id(ptr_db);
// pthread_mutex_unlock(&db_t_lock);
printf("add record (%llu,%d) ok.",update_id,item);
}
像节目输出错误:
[Thread debugging using libthread_db enabled]
[New Thread 0xb7ae3b70 (LWP 7712)]
Hello world!
[New Thread 0xb72d6b70 (LWP 7713)]
[New Thread 0xb6ad5b70 (LWP 7714)]
[New Thread 0xb62d4b70 (LWP 7715)]
[Thread 0xb7ae3b70 (LWP 7712) exited]
producer...
producer...
consumer...consumer...add record (31441,0) ok.add record (31442,1) ok.producer...
producer...
consumer...consumer...add record (31443,2) ok.add record (31444,3) ok.producer...
producer...
consumer...consumer...add record (31445,4) ok.add record (31446,5) ok.producer...
producer...
consumer...consumer...add record (31447,6) ok.add record (31448,7) ok.producer...
Error in my_thread_global_end(): 2 threads didn't exit
[Thread 0xb72d6b70 (LWP 7713) exited]
[Thread 0xb6ad5b70 (LWP 7714) exited]
[Thread 0xb62d4b70 (LWP 7715) exited]
Program exited normally.
,当我在功能addRecord_d的pthread_mutex_lock添加,错误依然存在。 那究竟是什么问题呢?
嗨迈克,谢谢你的帮助。 当我用上面提供的代码替换相应的代码时,会创建四个线程并很快出现,输出结果就是“hello world”。 所以我觉得可能会有一些错误的主要方法,真的,我忘了补充join方法,所以我跑终止的主要方法,而其他三个线程仍然活着的风险。 将pthread_join()添加到主方法的末尾,错误不再发生。 嗯,我是多线程编程的新手,你的回复让我想起了加入方法,谢谢。 – user188916 2009-12-17 03:16:02
以及即时通讯尝试在我的另一个测试源上使用你的建议,但一旦它运行mysql说“太多连接”,你有更好的主意吗? – capede 2011-06-18 18:19:46