WebSockets & Realtime Systems Programming · 课时

WebSockets 负载测试与容量规划

学习如何模拟数千个并发 WebSocket 连接、测量服务器限制并规划容量，让实时系统扩展时不再出现意外。

WebSockets 负载测试与容量规划 是 CoddyKit 上的免费 WebSockets & Realtime Systems Programming 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 WebSockets & Realtime Systems Programming 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 WebSockets & Realtime Systems Programming 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Why Load Testing Matters

Benchmarking tells you how a single connection behaves, but load testing tells you what happens when thousands of clients connect at once.

Find the breaking point before users do
Validate horizontal scaling assumptions
Size your infrastructure budget accurately

Connections vs Messages

Two independent dimensions stress a realtime server differently:

Connection count drives memory and file-descriptor usage
Message throughput drives CPU and network bandwidth

Always test both axes separately and combined.

Choosing a Load Tool

Popular WebSocket load tools include artillery, k6, and websocket-bench. They open many sockets and report latency percentiles.

# Install artillery
npm install -g artillery
artillery --version

A Basic Artillery Scenario

This YAML config ramps up to 500 new connections per second for 60 seconds and sends a join message.

config:
  target: 'ws://localhost:8080'
  phases:
    - duration: 60
      arrivalRate: 500
scenarios:
  - engine: ws
    flow:
      - send: '{"type":"join","room":"load"}'

Scripting Connections in Node

You can also script load tests manually for full control over message timing.

const WebSocket = require('ws');
const TOTAL = 1000;
let open = 0;
for (let i = 0; i < TOTAL; i++) {
  const ws = new WebSocket('ws://localhost:8080');
  ws.on('open', () => { open++; if (open === TOTAL) console.log('all connected'); });
}

Measuring Latency Percentiles

Averages hide pain. Report p50, p95, and p99 latency. A good p50 with a terrible p99 means some users have a bad experience.

Watching Server Resources

During a test, monitor the server side too: CPU, RSS memory, open file descriptors, and event-loop lag.

# Count open sockets for a process
lsof -p $(pgrep -f node) | grep -c TCP

File Descriptor Limits

Each connection consumes a file descriptor. The default OS limit (often 1024) will cap your connections long before CPU does.

# Inspect and raise the soft limit
ulimit -n
ulimit -n 100000

Finding the Breaking Point

Increase load in steps until latency spikes or connections start dropping. That inflection point is your per-node capacity.

Record the connection count at first failure
Leave a safety margin of 30-50%

From Capacity to Node Count

Capacity planning is arithmetic once you know per-node limits.

const peakUsers = 80000;
const perNode = 10000;
const safety = 0.6; // use 60% of measured max
const nodes = Math.ceil(peakUsers / (perNode * safety));
console.log('nodes needed:', nodes);

Testing in a Realistic Environment

Run load tests against staging hardware that mirrors production, and generate load from multiple machines so the client is never the bottleneck.

Quick Check

Which OS limit most commonly caps WebSocket connection counts first?

Recap

You learned to load test and plan capacity for WebSocket systems:

Test connection count and message throughput separately
Report p95/p99 latency, not averages
Raise file descriptor limits before testing
Find the breaking point and size node count with a safety margin

常见问题解答

「WebSockets 负载测试与容量规划」课时是免费的吗？

是的 — 「WebSockets 负载测试与容量规划」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 WebSockets & Realtime Systems Programming 课程的其余内容，请升级到 CoddyKit PRO。 WebSockets & Realtime Systems Programming 课程共包含 4 节课。

「WebSockets 负载测试与容量规划」这节课中我会学到什么？

学习如何模拟数千个并发 WebSocket 连接、测量服务器限制并规划容量，让实时系统扩展时不再出现意外。你通过在浏览器中直接运行的动手代码来练习 WebSockets & Realtime Systems Programming，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 WebSockets & Realtime Systems Programming 需要有经验吗？

无需任何先前经验。CoddyKit 上的 WebSockets & Realtime Systems Programming 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「WebSockets 负载测试与容量规划」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 WebSockets & Realtime Systems Programming 课中编写并运行代码吗？

能。每节 WebSockets & Realtime Systems Programming 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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