In my last post " Performance Comparison of Condition Variables and Atomics in C++20", I implemented a ping-pong game. Let me make a small performance test by playing ping-pong with semaphores.
This means, that the call prepareSignal.release() sets the value to 1 (line 2) and unblocks the call prepareSignal.acquire() (line 3). In the concrete example, it's initialized with 0 (line 1). The std::counting_semaphore prepareSignal (1) can have the values 0 oder 1. Std ::cout << "Waiter: Complete the work." << '\n' įor ( auto i : myVec) std ::cout << i << " " Std ::cout << "Waiter: Waiting for data." << '\n' Std ::cout << "Sender: Data prepared." << '\n'
Std ::counting_semaphore prepareSignal( 0) // (1) void prepareWork() ) threadSynchronizationSemaphore.cpp #include #include #include #include Blocked threads are added to the queue to avoid starvation. signal releases the semaphore and increases the counter. wait acquires the semaphore and decreases the counter it blocks the thread acquiring the semaphore if the counter is zero. It supports the two operations wait and signal. The counter is initialized to a value equal to or greater than zero. A semaphore is a data structure with a queue and a counter. Dijkstra presented in 1965 the concept of a semaphore. If a thread tries to acquire the semaphore when the counter is zero, the thread will block until another thread increments the counter by releasing the semaphore. Acquiring the semaphore decreases the counter and releasing the semaphore increases the counter. The counter is initialized in the constructor. They also allow it to play ping-pong.Ī counting semaphore is a special semaphore that has a counter that is bigger than zero. Semaphores are a synchronization mechanism used to control concurrent access to a shared resource.
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