No Cords Attached: Coordination-Free Concurrent Lock-Free Queues
Yusuf Motiwala

TL;DR
This paper presents CMP, a coordination-free lock-free queue that maintains FIFO order, unbounded capacity, and high scalability, significantly reducing complexity and overhead in highly concurrent AI workloads.
Contribution
Introduction of CMP, a simple, coordination-free lock-free queue that guarantees FIFO semantics with practical reclamation, improving scalability and reducing complexity.
Findings
CMP outperforms state-of-the-art queues by up to 4x under high contention.
CMP maintains scalability to hundreds of threads.
The approach simplifies concurrent queue design without sacrificing correctness.
Abstract
The queue is conceptually one of the simplest data structures-a basic FIFO container. However, ensuring correctness in the presence of concurrency makes existing lock-free implementations significantly more complex than their original form. Coordination mechanisms introduced to prevent hazards such as ABA, use-after-free, and unsafe reclamation often dominate the design, overshadowing the queue itself. Many schemes compromise strict FIFO ordering, unbounded capacity, or lock-free progress to mask coordination overheads. Yet the true source of complexity lies in the pursuit of infinite protection against reclamation hazards--theoretically sound but impractical and costly. This pursuit not only drives unnecessary complexity but also creates a protection paradox where excessive protection reduces system resilience rather than improving it. While such costs may be tolerable in conventional…
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Taxonomy
TopicsDistributed systems and fault tolerance · Software System Performance and Reliability · Parallel Computing and Optimization Techniques
