In this pattern, multiple readers can read the data in parallel but an exclusive lock is needed while writing the data. When a writer is writing the data, readers will be blocked until the writer is finished writing.

The current edition of the POSIX standard includes a read-write lock in the form of pthread_rwlock_t and the associated operations

Java version 5 or above includes an interface named java.util.concurrent.locks.ReadWriteLock that allows the use of this pattern.

Also, the Boost C++ Libraries include a read/write lock in the form of boost::shared_mutex

See also

• Lock pattern
• Semaphore
• Mutex
• Scheduler pattern
• Balking pattern
• Lock (software engineering)

External links

• Good explanation of the implementation of a read/write lock