Course contents

01Java Fundamentals
Module overview
02Core Java & OOP
Module overview
03Collections & Generics
Module overview
04Functional Java (8+)
Module overview
05Multithreading & Concurrency
Module overview
06JVM Internals & Memory
Module overview
07Java Performance Engineering
Module overview
1. Performance mindset
  1. Latency vs throughput
  2. Percentiles and tail latency
  3. Measure first: a performance workflow
  4. Little's law and capacity
  5. Interview questions & scenariosInterview
2. Finding bottlenecks
  1. CPU-bound bottlenecks
  2. Allocation and memory bottlenecks
  3. I/O-bound bottlenecks
  4. Lock contention
  5. GC pauses
  6. Interview questions & scenariosInterview
3. Tooling
  1. Java Flight Recorder and Mission Control
  2. How to read a flame graph
  3. async-profiler in practice
  4. jcmd, jstat and VisualVM
  5. Benchmarking with JMH
  6. Interview questions & scenariosInterview
4. Memory footprint
  1. Object overhead and compressed oops
  2. Boxing vs primitives
  3. Sizing collections
  4. String memory optimisations
  5. Off-heap memory
  6. Interview questions & scenariosInterview
5. CPU & JIT
  1. JIT-friendly code
  2. Inlining and megamorphic calls
  3. False sharing
  4. Interview questions & scenariosInterview
6. Concurrency performance
  1. Reducing contention
  2. Tuning thread pools
  3. Virtual threads for I/O-heavy services
  4. Interview questions & scenariosInterview
7. I/O & serialization
  1. Buffering and batching I/O
  2. Serialization and JSON costs
  3. Connection pools
  4. Interview questions & scenariosInterview
8. GC tuning
  1. Java memory management: heap, G1 and the signals that matter
  2. Heap sizing
  3. Pause-time goals
  4. Allocation rate and GC pressure
  5. Interview questions & scenariosInterview
9. Case studies
  1. Case study: the slow endpoint
  2. Case study: memory keeps growing
  3. Case study: the CPU spike
  4. Case study: thread pool exhaustion
  5. Interview questions & scenariosInterview
10. Module interview question bank
  1. Complete interview question bankBank
08Java I/O & NIO
Module overview
09Modern Java (17 → 21+)
Module overview
10Design Patterns & SOLID
Module overview
11Real-world Java & Interview Arsenal
Module overview
12Last-Mile Java: What You Can't Skip Before the Interview
Module overview

Module 07

Java Performance Engineering

Find and fix bottlenecks the way high-scale teams do: measure, profile, reduce memory footprint and tune, with real case studies.

Premium5 free lessons9 topics46 lessons & question sets2 ready

By the end of this module you can

Measure before optimising, with the right metrics and tools
Find CPU, memory, I/O and contention bottlenecks
Reduce memory footprint and GC pressure in real code

Performance mindset

Latency, throughput, percentiles and measuring first.

Latency vs throughputLessonFreeSoon
Percentiles and tail latencyLessonFreeSoon
Measure first: a performance workflowLessonFreeSoon
Little's law and capacityLessonPremiumSoon
Performance mindset: interview questions & scenariosInterview Q&APremiumSoon

Finding bottlenecks

Recognising CPU, memory, I/O, contention and GC problems.

CPU-bound bottlenecksLessonPremiumSoon
Allocation and memory bottlenecksLessonPremiumSoon
I/O-bound bottlenecksLessonPremiumSoon
Lock contentionLessonPremiumSoon
GC pausesLessonPremiumSoon
Finding bottlenecks: interview questions & scenariosInterview Q&APremiumSoon

Tooling

Profilers, flame graphs and benchmarking done right.

Java Flight Recorder and Mission ControlLessonPremiumSoon
How to read a flame graphLesson · 15 minFree
async-profiler in practiceLessonPremiumSoon
jcmd, jstat and VisualVMLessonPremiumSoon
Benchmarking with JMHLessonPremiumSoon
Tooling: interview questions & scenariosInterview Q&APremiumSoon

Memory footprint

Making the same work use less memory.

Object overhead and compressed oopsLessonPremiumSoon
Boxing vs primitivesLessonPremiumSoon
Sizing collectionsLessonPremiumSoon
String memory optimisationsLessonPremiumSoon
Off-heap memoryLessonPremiumSoon
Memory footprint: interview questions & scenariosInterview Q&APremiumSoon

CPU & JIT

Writing code the JIT can optimise.

JIT-friendly codeLessonPremiumSoon
Inlining and megamorphic callsLessonPremiumSoon
False sharingLessonPremiumSoon
CPU & JIT: interview questions & scenariosInterview Q&APremiumSoon

Concurrency performance

Scaling with threads instead of fighting them.

Reducing contentionLessonPremiumSoon
Tuning thread poolsLessonPremiumSoon
Virtual threads for I/O-heavy servicesLessonPremiumSoon
Concurrency performance: interview questions & scenariosInterview Q&APremiumSoon

I/O & serialization

The hidden cost of I/O, JSON and connections.

Buffering and batching I/OLessonPremiumSoon
Serialization and JSON costsLessonPremiumSoon
Connection poolsLessonPremiumSoon
I/O & serialization: interview questions & scenariosInterview Q&APremiumSoon

GC tuning

Heap sizing, pause goals and allocation rate.

Java memory management: heap, G1 and the signals that matterLesson · 21 minFree
Heap sizingLessonPremiumSoon
Pause-time goalsLessonPremiumSoon
Allocation rate and GC pressureLessonPremiumSoon
GC tuning: interview questions & scenariosInterview Q&APremiumSoon

Case studies

Real incidents from symptom to root cause to fix.

Case study: the slow endpointLessonPremiumSoon
Case study: memory keeps growingLessonPremiumSoon
Case study: the CPU spikeLessonPremiumSoon
Case study: thread pool exhaustionLessonPremiumSoon
Case studies: interview questions & scenariosInterview Q&APremiumSoon

Finish the module

Module interview question bank

Every interview question worth practising for Java Performance Engineering, grouped by topic, with model answers, how to say them and what-if follow-ups.

Being written: it grows as the topics in this module are finished

PremiumSoon