0%

pthread_mutex_t 属性

Posted on Edited on In
Symbols count in article: 804 Reading time ≈ 1 mins. 
/* Mutex types.  */
enum
{
  PTHREAD_MUTEX_TIMED_NP,
  PTHREAD_MUTEX_RECURSIVE_NP,
  PTHREAD_MUTEX_ERRORCHECK_NP,
  PTHREAD_MUTEX_ADAPTIVE_NP
#if defined __USE_UNIX98 || defined __USE_XOPEN2K8
  ,
  PTHREAD_MUTEX_NORMAL = PTHREAD_MUTEX_TIMED_NP,
  PTHREAD_MUTEX_RECURSIVE = PTHREAD_MUTEX_RECURSIVE_NP,
  PTHREAD_MUTEX_ERRORCHECK = PTHREAD_MUTEX_ERRORCHECK_NP,
  PTHREAD_MUTEX_DEFAULT = PTHREAD_MUTEX_NORMAL
#endif
#ifdef __USE_GNU
  /* For compatibility.  */
  , PTHREAD_MUTEX_FAST_NP = PTHREAD_MUTEX_TIMED_NP
#endif
};

attr

  • DEFAULT 与 NORMAL 属性有太多的未定义行为，应该尽可能的避免使用。NORMAL 会导致死锁，并不会返回错误代码，因而程序会卡住。互斥锁默认属性为 NORMAL
  • ERRORCHECK 重复加锁，重复解锁都会返回错误代码，不会导致死锁
  • RECURSIVE 允许同一线程进行N次加锁，但必须进行N次解锁才能释放这把锁
pthread_mutexattr_settype(&mutex_attr, PTHREAD_MUTEX_ERRORCHECK);

Ref

  1. POS04-C. Avoid using PTHREAD_MUTEX_NORMAL type mutex locks
  2. pthread_mutex_lock
  3. POSIX 设置锁的属性
  4. pthread_mutexattr_settype(3) - Linux man page