Lesson 18/100

Tutorials ML.NET Tutorial

Training vs Inference — Complete Guide

Training vs Inference — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ML.NET Tutorial on Toolliyo Academy.

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ML.NET Tutorial · Lesson 18 of 100

Training vs Inference

FoundationsModelsNLP & advancedMLOps

Foundations · 1 — Context & data · ~6 min · Module 2: Machine Learning Basics

What is this?

Training Fits a model from labeled data; inference Transforms/Predicts on new rows with a frozen model.

Why should you care?

AIPredict trains offline nightly; APIs only run inference for low latency.

See it live — copy this example

Use a .NET console or Web API project with Microsoft.ML. Run dotnet run after pasting.

// Training job
var model = pipeline.Fit(train);
ml.Model.Save(model, train.Schema, "fraud.zip");
// API inference
var loaded = ml.Model.Load("fraud.zip", out _);
var pred = ml.Model.CreatePredictionEngine<Tx, Score>(loaded).Predict(tx);

What happened?

  • Never Fit inside a customer request.
  • Warm PredictionEngine or use PredictionEnginePool in ASP.NET Core.

Practice next

  1. Separate TrainWorker vs Api projects.
  2. Save zip from worker.
  3. API only Load/Predict.
  4. Time Fit vs Predict once.
  5. Document model path env var.

Remember

Train offline. Infer online. Pool engines in web.

AIPredict train/infer split

Worker writes fraud.zip; API scores.

Outcome: p95 stays milliseconds.

Interview prep for this lesson

Practice these questions aloud after reading—each links to a full structured answer.

Junior Detailed
Explain Concepts in the context of ML.NET.
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define Concepts…
Mid Detailed
What are common mistakes teams make with LLMs when using ML.NET?
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define LLMs in p…
Senior Detailed
How would you debug a production issue related to RAG in a ML.NET application?
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define RAG in pl…
Junior Detailed
Describe a real-world scenario where Production mattered in a ML.NET project.
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define Productio…
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ML.NET Tutorial
Course syllabus
Module 1: ML.NET Foundations
Module 2: Machine Learning Basics
Module 3: ML.NET Pipelines
Module 4: Classification Models
Module 5: Regression Models
Module 6: Recommendation Systems
Module 7: NLP with ML.NET
Module 8: Advanced ML.NET
Module 9: ASP.NET Core AI Integration
Module 10: MLOps & Cloud AI
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