Real-Time Online Inference
Serve low-latency predictions per request.
Real-Time Online Inference is a free MLOps Academy lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the MLOps Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What Online Inference Is
Online inference answers one request at a time, the instant it arrives, so a user or service gets a fresh prediction right away. ⚡
A User Is Waiting
Unlike batch, here someone waits on the other end. The prediction must come back in milliseconds, not minutes, to feel responsive.
It Lives Behind an API
An online model sits behind an HTTP endpoint. A client sends features in a request and gets the prediction back in the response.
# POST /predict {"features": [5.1, 3.5, 1.4]}One Request, One Prediction
Each call carries the input for a single case. The service runs predict on it and returns the score, then handles the next caller.
def predict(req):
x = parse(req.features)
return model.predict([x])[0]Always Fresh Inputs
Because features arrive with the request, the score reflects the latest state, perfect when inputs change second to second.
Latency Is the Metric
The number you watch is latency: how long from request to response. People often track the slow 95th and 99th percentile, not just the average.
Load the Model Once
Loading the model on every request would be slow. Instead you load it once at startup and reuse it across all incoming calls.
Concurrency Matters
Many users hit the service at the same time. It must serve requests concurrently, often with multiple workers, to keep latency low under load.
Real-World Examples
Fraud checks at checkout, search ranking, and recommendation widgets all need instant answers, so they run as online inference.
The Cost of Being Live
An online service must stay running and ready around the clock. That always-on footprint costs more than a job that runs and stops.
When to Pick Online
Choose online when inputs are unknown ahead of time and users need a fresh answer now, accepting more cost and operational care.
Quick Check
What metric matters most for online inference?
Recap
Online inference serves one fresh prediction per request behind an API, prizes low latency, and costs more because it must stay always on.
Frequently asked questions
Is the “Real-Time Online Inference” lesson free?
Yes — the full text of “Real-Time Online Inference” is free to read here on the web, and the MLOps Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the MLOps Academy course, upgrade to CoddyKit PRO.
What will I learn in “Real-Time Online Inference”?
Serve low-latency predictions per request. You practise MLOps Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start MLOps Academy?
No prior experience is required. MLOps Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Real-Time Online Inference” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this MLOps Academy lesson?
Yes. Every MLOps Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Batch Scoring on a Schedule
- Real-Time Online Inference
- Latency, Throughput, and Cost Trade-offs
- Precompute and Cache Predictions