多線之間的數據共享,除此之外,還有信號量共享的問題。下面的代碼是有問題的。
class cthread1{
void start();
void thread_proc();
private:
sem_t* psem;
};
static void *do_thread1(void* data){
cthread1* ptread = (cthread1*)data;
pthread->thread_proc();
}
void cthread1:start(){
psem = sem_open("http", O_CREAT, 0644, 1);
pthread_t thread_t;
pthread_create(&thread_t, NULL, do_thread1, this);
pthread_detach(thread_t);
}
void cthread1:thread_proc(){
//use psem,do somthing.
}
class cthread2{
void start();
void thread_proc();
private:
sem_t* psem;
};
static void *do_thread2(void* data){
cthread2* ptread = (cthread2*)data;
pthread->thread_proc();
}
void cthread2:start(){
psem = sem_open("http", O_CREAT, 0644, 1);
pthread_t thread_t;
pthread_create(&thread_t, NULL, do_thread2, this);
pthread_detach(thread_t);
}
void cthread2:thread_proc(){
//use psem,do somthing.
}
因爲psem是個共享內存信號量,名字一樣的話,兩個類裏的psem是一樣的,這是個很低級的BUG, 常常由於拷貝粘貼而沒有注意同名導致。