This example shows a Pthread program using condition variables to notify threads of a condition. Notice what mutual exclusion (mutex) locking protocol is used.
1. 首先pthread_cond_wait 的定义是这样的 The pthread_cond_wait()andpthread_cond_timedwait()functions are used to block on a condition variable. They are called withmutexlocked by the calling thread or undefined behaviour will result. These functions atomically releasemutexand cause the calling thre...
当多个线程协作时,相互作用的任务必须在一定的条件下同步。 Linux下的C语言编程有多种线程同步机制,最典型的是条件变量(condition variable)。pthread_cond_init用来创建一个条件变量,其函数原型为: pthread_cond_init (pthread_cond_t *cond, const pthread_condattr_t *attr); pthread_cond_wait和pthread_cond_t...
pthread_cond_wait()的工作流程如下(以MAN中的EXAMPLE为例): Consider two shared variables x and y, protected by the mutex mut, and a condition vari- able cond that is to be signaled whenever x becomes greater than y. int x,y; pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER; pthread_cond...
此外,还可以使用条件变量(Condition Variable)来实现线程之间的同步。条件变量可以让线程在等待某个条件满足时进入阻塞状态,避免忙等的情况发生,提高程序的效率。 最后,在编译多线程程序时,可以通过 -D_REENTRANT 宏来告知编译器进行多线程支持。这个宏定义会启用对线程安全和可重入函数的支持,确保程序在多线程环境下能...
答案2:在Windows上,使用POSIX的pthread库实现多线程代码的同步和互斥操作可以通过使用互斥锁(Mutex)和条件变量(Condition Variable)来实现。 互斥锁可以用于保护共享资源,确保只有一个线程可以访问该资源。可以使用pthread_mutex_init函数来初始化互斥锁,使用pthread_mutex_lock和pthread_mutex_unlock函数来加锁和解锁互斥锁...
(3) Condition Variable(条件变量):pthread_con_*** (4) Read/Write lock(读写锁):pthread_rwlock_*** Pthreads提供的Mutex锁操作相关的API主要有: pthread_mutex_lock (pthread_mutex_t *mutex); pthread_mutex_trylock (pthread_mutex_t *mutex); ...
(3) Condition Variable(条件变量):pthread_con_*** (4) Read/Write lock(读写锁):pthread_rwlock_*** Pthreads提供的Mutex锁操作相关的API主要有: pthread_mutex_lock (pthread_mutex_t *mutex); pthread_mutex_trylock (pthread_mutex_t *mutex); ...
Condition Variable Broadcast Example Sincepthread_cond_broadcast()causes all threads blocked on the condition to contend again for the mutex lock, use it with care. For example, usepthread_cond_broadcast()to allow threads to contend for varying resource amounts when resources are freed, as shown...
The pthread_cond_wait() and pthread_cond_timedwait() functions are used to block on a condition variable. They are called with mutex locked by the calling thread or undefined behaviour will result. These functions atomically release mutex and cause the calling thread to block on the condition...