Concurrent collections and synchronization primitives for writing fast multithreaded and asynchronous code. This library is experimental and provided without warranty, so use it carefully.

• lockless semaphores
• priority semaphore
• lockless object and array pools
• memory compact single writer multiple readers hash map
• memory compact thread safe (but locked) hash map
• write optimized lock-free counter

• QueueSemaphore: uses ConcurrentQueue to order waiters
• StackSemaphore: uses ConcurrentStack to order waiters
• SimpleSegmentSemaphore: uses segment queue to order waiters (similar to the Semaphore from kotlinx.coroutines)
• SegmentSemaphore: uses segment queue with support of early removal of cancelled waiters
• PrioritySemaphore: lock-based semaphore (like SemaphoreSlim), but releases waiters in specified priority

• LocklessArrayPool<T>.Shared: similar to ArrayPool<T>.Shared but uses bounded concurrent queue instead of lock protected arrays to store pooled items.
• IObjectPool<T>, ObjectPool<T>

• SingleWriterDictionary<TKey, TValue, TComparer>: memory-compact hash map that supports single writer and multiple readers simultaneously. Writes are lock-free (except for resizes, which may trigger GC), but reads may be retried when a parallel update occurs.
• StripedDictionary<TKey, TValue, TComparer>: memory-compact hash map, designed to avoid ConcurrentDictionary GC overhead. It is not general purpose ConcurrentDictionary replacement, and generally is slower, especially for reads.
• DefaultComparer<TKey>: default comparer for ConcurrencyToolkit hash maps
• ComparerWrapper<TKey>: struct wrapper over the reference type comparer

• ThreadSafeCounter64: scalable atomic counter that distributes writes across per-core variables

• InterlockedFloatingPoint: methods for atomic floating point arithmetics
• LowLatencySpinWait: SpinWait implementation that achieves low latency (~0.5ms) on sleeps instead of standard 15ms