互斥鎖是Linux下多線程資源保護的常用手段，但是在時序復雜的情況下，很容易會出現死鎖的情況。
可以通過設置鎖的屬性，避免同一條線程重復上鎖導致死鎖的問題。
通過int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type)接口設置
一般是以下四種屬性：
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PTHREAD_MUTEX_NORMALThis type of mutex does not detect deadlock. A thread attempting to relock this mutex without first unlocking it will deadlock. Attempting to unlock a mutex locked by a different thread results in undefined behaviour. Attempting to unlock an unlocked mutex results in undefined behaviour.PTHREAD_MUTEX_ERRORCHECKThis type of mutex provides error checking. A thread attempting to relock this mutex without first unlocking it will return with an error. A thread attempting to unlock a mutex which another thread has locked will return with an error. A thread attempting to unlock an unlocked mutex will return with an error.PTHREAD_MUTEX_RECURSIVEA thread attempting to relock this mutex without first unlocking it will succeed in locking the mutex. The relocking deadlock which can occur with mutexes of type PTHREAD_MUTEX_NORMAL cannot occur with this type of mutex. Multiple locks of this mutex require the same number of unlocks to release the mutex before another thread can acquire the mutex. A thread attempting to unlock a mutex which another thread has locked will return with an error. A thread attempting to unlock an unlocked mutex will return with an error.PTHREAD_MUTEX_DEFAULTAttempting to recursively lock a mutex of this type results in undefined behaviour. Attempting to unlock a mutex of this type which was not locked by the calling thread results in undefined behaviour. Attempting to unlock a mutex of this type which is not locked results in undefined behaviour. An implementation is allowed to map this mutex to one of the other mutex types. |
這里主要指同一條線程重復上鎖，不同線程上鎖，無論設置什么屬性，當鎖已經被鎖定后都會互斥阻塞。
使用PTHREAD_MUTEX_RECURSIVE屬性，當同一條線程在沒有解鎖的情況下嘗試再次鎖定會返回成功。
以上就是小編為大家帶來的Linux多線程鎖屬性設置方法全部內容了，希望大家多多支持服務器之家~
