Why is there no read-write lock in Linux thread synchronization method?

The Linux thread synchronization method does not have read-write locks because in the Linux thread model, more emphasis is placed on ensuring the atomic operation of data and thread safety, rather than directly providing read-write locks. mechanism.

The operating system of this tutorial: Linux5.18.14 system, Dell G3 computer.

In Linux, thread synchronization is achieved through various mechanisms, including mutex (Mutex), condition variable (Condition Variable), semaphore (Semaphore), etc. Although there is the concept of read-write lock (Read-Write Lock), there is no direct read-write lock mechanism in Linux.

This is because in the Linux thread model, more emphasis is placed on the atomic operation of data and the guarantee of thread safety, rather than directly providing mechanisms such as read-write locks. In Linux, mutex locks can be used to synchronize read and write operations on shared resources.

Using mutex locks for read and write synchronization may have some impacts:

• Performance overhead: Mutex locks are a relatively heavy synchronization mechanism. When multiple threads simultaneously request read operations on a shared resource, using a mutex for synchronization may result in increased performance overhead. Because the mutex lock only allows one thread to access the shared resource at the same time, other threads must wait for the lock to be released.

• Write-read mutex: When using a mutex lock for read-write synchronization, write operations and read operations are mutually exclusive. This means that while one thread is performing a write operation, other threads cannot perform read operations, and multiple threads will be blocked even if they only need to read data. This may reduce parallelism and the throughput of the system.

• Potential deadlock: If the mutex lock is used improperly, it may lead to deadlock. For example, if a thread requests a read lock while holding a write lock, and other threads request a write lock while waiting for this thread to release the write lock, this will cause a deadlock.

Nonetheless, Linux provides a variety of other synchronization mechanisms, such as condition variables and semaphores, which can be used to more finely control synchronization and communication between threads. Based on actual needs and scenarios, developers can choose an appropriate synchronization mechanism to ensure data consistency and security between threads.

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