NumaScheduler 1.0.0

NumaScheduler

A cross-platform .NET TaskScheduler that pins worker threads to NUMA nodes, keeping task execution and memory access local to the same CPU socket. Supports Windows, Linux, and falls back gracefully on macOS and other platforms.

Why NUMA-aware scheduling?

On multi-socket servers, accessing memory attached to a remote NUMA node is significantly slower than accessing local memory. By keeping threads and their data on the same node you reduce cross-socket memory traffic and improve throughput and latency for data-intensive workloads.

Supported platforms

Target frameworks

netstandard2.0 · net8.0 · net9.0 · net10.0

Installation

dotnet add package NumaScheduler

Quick start

1. Inspect topology

var topology = NumaTopology.Instance;

Console.WriteLine($"NUMA nodes: {topology.NodeCount}, IsNumaSystem: {topology.IsNumaSystem}");
foreach (var node in topology.Nodes)
    Console.WriteLine(node); // "NUMA Node 0 | 16 logical CPU(s) | ..."

2. Policy-driven scheduler (recommended)

// One thread pool per NUMA node; tasks routed to the calling thread's local node.
using var scheduler = new NumaAwareTaskScheduler(NumaSchedulingPolicy.LocalityFirst);

var task = Task.Factory.StartNew(() =>
{
    // Runs on the NUMA node closest to the enqueueing thread.
}, CancellationToken.None, TaskCreationOptions.PreferFairness, scheduler);

await task;

Available policies:

3. Pin a task to a specific node

// Bypass the policy and force execution on node 1.
await NumaAwareTaskScheduler.Shared.RunOnNode(nodeIndex: 1, () =>
{
    ProcessChunk(data);
});

// Generic overload returns a result.
double result = await NumaAwareTaskScheduler.Shared.RunOnNode(1, () => ComputeSum(data));

4. Extension methods

// Run on a specific node using the global Shared scheduler.
await ((Action)(() => Process(data))).RunOnNumaNode(nodeIndex: 0);

// Use LocalityFirst policy via the global Shared scheduler.
await ((Action)(() => Process(data))).RunNumaLocal();

5. Standalone per-node scheduler

Useful when you need a plain TaskScheduler reference for an API that doesn't accept NumaAwareTaskScheduler.

var node = NumaTopology.Instance.Nodes[0];

using var nodeScheduler = new NumaNodeScheduler(node, threadCount: 4);

await Task.Factory.StartNew(() => Work(), CancellationToken.None,
    TaskCreationOptions.None, nodeScheduler);

6. Process-wide singleton

NumaAwareTaskScheduler.Shared is a lazily-initialised process-lifetime singleton using LocalityFirst.
Do not dispose it.

await Task.Factory.StartNew(Work, CancellationToken.None,
    TaskCreationOptions.PreferFairness, NumaAwareTaskScheduler.Shared);

Diagnostics

foreach (var (nodeId, pending) in scheduler.GetNodeStats())
    Console.WriteLine($"Node {nodeId}: {pending} pending tasks");

Thread safety

All public types are thread-safe. Dispose may be called from any thread; subsequent calls are no-ops.

License

MIT © 2026 Zoltan Csizmadia