Lock Free Ring Buffers

Lock-Free Architecture & Ring Buffers

Core Mechanics

Mutexes and Locks pause threads. In HFT systems, locking causes latency spikes (jitter). To process millions of orders per second, architectures must be Lock-Free.

1. The LMAX Disruptor

A revolutionary architecture for high-performance inter-thread communication.

• Ring Buffer: A pre-allocated, circular array. No garbage collection, no memory allocation during runtime.
• Sequence Barriers: Instead of locks, threads track atomic Sequence counters to know which slot in the array they are allowed to read or write.

2. Mechanical Sympathy (CPU Caches)

The Disruptor respects hardware. By padding data structures to 64 bytes (the size of a CPU Cache Line), it prevents "False Sharing"—a hardware phenomenon where two CPU cores accidentally invalidate each other's cache because they are modifying adjacent variables.

Ring Buffer Architecture Map

%%{init: {"theme": "default", "flowchart": {"useMaxWidth": true}}}%%
flowchart TD
    subgraph DataStructure ["Pre-allocated Ring Buffer"]
        A["Slot 0"]
        B["Slot 1"]
        C["Slot 2"]
        D["Slot N..."]
    end
    
    subgraph Threads ["Concurrent Lock-Free Access"]
        E["Publisher Thread (Write)"]
        F["Consumer Thread (Read)"]
    end
    
    subgraph Sync ["Atomic Sequences (CAS)"]
        G["Cursor (Head)"]
        H["Consumer Sequence (Tail)"]
    end
    
    E -->|"Claims Slot via CAS"| G
    G -.->|"Write Data"| B
    F -->|"Checks available slots"| H
    H -.->|"Read Data"| A