When writing multithreaded code, there are some common patterns and tricks that can help improve code readability, safety, and efficiency. Here are some patterns and techniques that are often used when writing thread loops:
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Condition variables : Condition variables are used to achieve synchronization between threads, which can prevent some threads from continuing to execute when a specific condition is not met. For example, if a thread needs to wait for other threads to complete some operations before it can run, you can use a condition variable to make the thread wait until the condition is met.
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Mutex (mutex) : Mutex is used to prevent multiple threads from accessing shared resources at the same time, thereby preventing data race conditions. In C++, you can use
std::unique_lockorstd::lock_guardto automatically manage the locking and unlocking of mutexes. -
Semaphore : A semaphore is a more complex thread synchronization mechanism that can be used to control the number of threads accessing a resource at the same time.
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Atomic operation : Atomic operation can ensure that in a multi-threaded environment, an operation will not be interrupted by other threads during execution. In C++, you can use
std::atomictemplates to create atomic variables. -
Thread pool : Creating and destroying threads may incur a large overhead, and the thread pool can reuse threads to improve efficiency. A thread pool is usually implemented using a task queue and a set of worker threads, which fetch tasks from the task queue for execution.
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Periodic wakeup and sleep : Sometimes, a thread may need to sleep while waiting for some event to occur, and then wake up periodically to check whether the event has occurred. This can be achieved through condition variables or
std::this_thread::sleep_for.