Queuek

Queuek is a generalized queuing data structure used in computer science to manage work items by distributing them into k parallel sub-queues. Each sub-queue corresponds to a priority level or class, with the parameter k indicating the number of classes. The design allows flexible scheduling policies that determine how items are selected for processing across sub-queues.

Operations in a queuek system include Enqueue, which places an item into the designated sub-queue based on attributes such as priority, class, or a dynamic mapping. Dequeue selects the next item to process according to a policy, which may be strict priority (always serving from the highest non-empty queue), round-robin among non-empty queues, or a weighted fair scheme giving each queue a share of service time. A peek operation and a size query may be provided as well.

Implementation and performance considerations: In a typical implementation, queuek is realized as an array of k standard queues. Enqueue is generally O(1). Dequeue complexity depends on the policy: strict priority can degrade to O(k) in the worst case, while round-robin or weighted policies can achieve near O(1) time with appropriate tracking. Memory usage scales with the total number of items plus the k queue structures. The policy choice affects fairness and latency.

Applications: Queuek is used in networking routers for class-based queuing, in operating systems for multi-class CPU scheduling, in print servers, and in multimedia streaming pipelines where different data streams require separate handling.

Variants and relation: Queuek relates to multi-queue and priority queue concepts. It can be viewed as a constrained form of a priority queue, or as a collection of queues with a unified interface. Dynamic adjustment of k or the mapping from items to queues can be supported to adapt to workload changes.