Concurrency control

Lock convoy

In computer science, a lock convoy is a performance problem that can occur when using locks for concurrency control in a multithreaded application. A lock convoy occurs when multiple threads of equal priority contend repeatedly for the same lock. Unlike deadlock and livelock situations, the threads in a lock convoy do progress; however, each time a thread attempts to acquire the lock and fails, it relinquishes the remainder of its scheduling quantum and forces a context switch. The overhead of repeated context switches and underutilization of scheduling quanta degrade overall performance. Lock convoys often occur when concurrency control primitives such as locks serialize access to a commonly used resource, such as a memory heap or a thread pool. They can sometimes be addressed by using non-locking alternatives such as lock-free algorithms or by altering the relative priorities of the contending threads. (Wikipedia).

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Related pages

Lock (computer science) | Deadlock | Thundering herd problem | Concurrency control