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Read-copy-update insertion procedure. A thread allocates a structure with three fields, then sets the global pointer gptr to point to this structure.. A key property of RCU is that readers can access a data structure even when it is in the process of being updated: RCU updaters cannot block readers or force them to retry their accesses.
In computer science, the thundering herd problem occurs when a large number of processes or threads waiting for an event are awakened when that event occurs, but only one process is able to handle the event. When the processes wake up, they will each try to handle the event, but only one will win.
An algorithm is lock-free if, when the program threads are run for a sufficiently long time, at least one of the threads makes progress (for some sensible definition of progress). All wait-free algorithms are lock-free. In particular, if one thread is suspended, then a lock-free algorithm guarantees that the remaining threads can still make ...
Alternatively an RW lock can be implemented in terms of a condition variable, cond, an ordinary (mutex) lock, g, and various counters and flags describing the threads that are currently active or waiting. [7] [8] [9] For a write-preferring RW lock one can use two integer counters and one Boolean flag:
Contention: some threads/processes have to wait until a lock (or a whole set of locks) is released. If one of the threads holding a lock dies, stalls, blocks, or enters an infinite loop, other threads waiting for the lock may wait indefinitely until the computer is power cycled.
Specifically, to acquire a lock, process i executes [4]: 22 i ← ProcessNo for ℓ from 0 to N − 1 exclusive level[i] ← ℓ last_to_enter[ℓ] ← i while last_to_enter[ℓ] = i and there exists k ≠ i, such that level[k] ≥ ℓ wait. To release the lock upon exiting the critical section, process i sets level[i] to −1.
In computing, cache replacement policies (also known as cache replacement algorithms or cache algorithms) are optimizing instructions or algorithms which a computer program or hardware-maintained structure can utilize to manage a cache of information. Caching improves performance by keeping recent or often-used data items in memory locations ...
In software engineering, a spinlock is a lock that causes a thread trying to acquire it to simply wait in a loop ("spin") while repeatedly checking whether the lock is available. Since the thread remains active but is not performing a useful task, the use of such a lock is a kind of busy waiting .