Course contents

01Java Fundamentals
Module overview
02Core Java & OOP
Module overview
03Collections & Generics
Module overview
04Functional Java (8+)
Module overview
05Multithreading & Concurrency
Module overview
1. Thread basics
  1. Beginner's guide to Java multithreading
  2. Processes vs threads
  3. Creating threads: Thread, Runnable and Callable
  4. Thread lifecycle and states
  5. Daemon threads and priorities
  6. Interrupts and cancellation
  7. Interview questions & scenariosInterview
2. Synchronization
  1. Race conditions
  2. synchronized and monitors
  3. Reentrancy
  4. wait(), notify() and notifyAll()
  5. Why wait() and notify() need synchronized
  6. The producer–consumer problem
  7. Interview questions & scenariosInterview
3. Java Memory Model
  1. Visibility and reordering
  2. Happens-before
  3. volatile
  4. Safe publication and double-checked locking
  5. final field semantics
  6. Interview questions & scenariosInterview
4. Atomics & CAS
  1. Atomic classes
  2. Compare-and-swap and the ABA problem
  3. LongAdder and striped counters
  4. Interview questions & scenariosInterview
5. Locks
  1. ReentrantLock and Condition
  2. ReadWriteLock
  3. StampedLock
  4. Lock fairness
  5. Interview questions & scenariosInterview
6. Liveness
  1. Deadlock detection and prevention
  2. Livelock and starvation
  3. Reading thread dumps
  4. Interview questions & scenariosInterview
7. Executors & thread pools
  1. ExecutorService and thread pools
  2. ThreadPoolExecutor internals
  3. Rejection policies
  4. Scheduled executors
  5. Sizing thread pools
  6. Interview questions & scenariosInterview
8. Coordination utilities
  1. CountDownLatch
  2. CyclicBarrier
  3. Semaphore
  4. Phaser
  5. Interview questions & scenariosInterview
9. Concurrent collections
  1. How ConcurrentHashMap works
  2. CopyOnWriteArrayList
  3. BlockingQueue implementations
  4. Interview questions & scenariosInterview
10. Async programming
  1. Future and Callable
  2. How CompletableFuture works
  3. Fork/Join and work stealing
  4. Interview questions & scenariosInterview
11. ThreadLocal
  1. ThreadLocal and InheritableThreadLocal
  2. ThreadLocal memory leaks
  3. Interview questions & scenariosInterview
12. Modern concurrency
  1. Virtual threads
  2. Structured concurrency and scoped values
  3. Interview questions & scenariosInterview
13. Concurrency coding problems
  1. Concurrency coding problems
  2. Interview questions & scenariosInterview
14. Module interview question bank
  1. Complete interview question bankBank
06JVM Internals & Memory
Module overview
07Java Performance Engineering
Module overview
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 05

Multithreading & Concurrency

From your first thread to the Java Memory Model, locks, executors, CompletableFuture and virtual threads, with many scenario questions.

Premium7 free lessons13 topics61 lessons & question sets2 ready

By the end of this module you can

Reason about visibility, ordering and happens-before
Choose between synchronized, locks, atomics and concurrent collections
Diagnose deadlocks and tune thread pools

Thread basics

Processes vs threads, creating threads, lifecycle and interrupts.

Beginner's guide to Java multithreadingFree guide · already liveFree
Processes vs threadsLessonFreeSoon
Creating threads: Thread, Runnable and CallableLessonFreeSoon
Thread lifecycle and statesLessonFreeSoon
Daemon threads and prioritiesLessonPremiumSoon
Interrupts and cancellationLessonPremiumSoon
Thread basics: interview questions & scenariosInterview Q&APremiumSoon

Synchronization

Race conditions, monitors, wait/notify and producer–consumer.

Race conditionsLessonFreeSoon
synchronized and monitorsLessonFreeSoon
ReentrancyLessonPremiumSoon
wait(), notify() and notifyAll()LessonPremiumSoon
Why wait() and notify() need synchronizedFree guide · already liveFree
The producer–consumer problemLessonPremiumSoon
Synchronization: interview questions & scenariosInterview Q&APremiumSoon

Java Memory Model

Visibility, reordering, happens-before, volatile and safe publication.

Visibility and reorderingLessonPremiumSoon
Happens-beforeLessonPremiumSoon
volatileLessonPremiumSoon
Safe publication and double-checked lockingLessonPremiumSoon
final field semanticsLessonPremiumSoon
Java Memory Model: interview questions & scenariosInterview Q&APremiumSoon

Atomics & CAS

Lock-free building blocks.

Atomic classesLessonPremiumSoon
Compare-and-swap and the ABA problemLessonPremiumSoon
LongAdder and striped countersLessonPremiumSoon
Atomics & CAS: interview questions & scenariosInterview Q&APremiumSoon

Locks

Explicit locks and when to use them.

ReentrantLock and ConditionLessonPremiumSoon
ReadWriteLockLessonPremiumSoon
StampedLockLessonPremiumSoon
Lock fairnessLessonPremiumSoon
Locks: interview questions & scenariosInterview Q&APremiumSoon

Liveness

Deadlock, livelock, starvation and thread dumps.

Deadlock detection and preventionLessonPremiumSoon
Livelock and starvationLessonPremiumSoon
Reading thread dumpsLessonPremiumSoon
Liveness: interview questions & scenariosInterview Q&APremiumSoon

Executors & thread pools

ExecutorService, ThreadPoolExecutor internals and sizing.

ExecutorService and thread poolsLessonPremiumSoon
ThreadPoolExecutor internalsLessonPremiumSoon
Rejection policiesLessonPremiumSoon
Scheduled executorsLessonPremiumSoon
Sizing thread poolsLessonPremiumSoon
Executors & thread pools: interview questions & scenariosInterview Q&APremiumSoon

Coordination utilities

Latches, barriers, semaphores and phasers.

CountDownLatchLessonPremiumSoon
CyclicBarrierLessonPremiumSoon
SemaphoreLessonPremiumSoon
PhaserLessonPremiumSoon
Coordination utilities: interview questions & scenariosInterview Q&APremiumSoon

Concurrent collections

ConcurrentHashMap internals, copy-on-write and blocking queues.

How ConcurrentHashMap worksLessonPremiumSoon
CopyOnWriteArrayListLessonPremiumSoon
BlockingQueue implementationsLessonPremiumSoon
Concurrent collections: interview questions & scenariosInterview Q&APremiumSoon

Async programming

Futures, CompletableFuture and Fork/Join.

Future and CallableLessonPremiumSoon
How CompletableFuture worksLessonPremiumSoon
Fork/Join and work stealingLessonPremiumSoon
Async programming: interview questions & scenariosInterview Q&APremiumSoon

ThreadLocal

Per-thread state and its pitfalls.

ThreadLocal and InheritableThreadLocalLessonPremiumSoon
ThreadLocal memory leaksLessonPremiumSoon
ThreadLocal: interview questions & scenariosInterview Q&APremiumSoon

Modern concurrency

Virtual threads, structured concurrency and scoped values.

Virtual threadsLessonPremiumSoon
Structured concurrency and scoped valuesLessonPremiumSoon
Modern concurrency: interview questions & scenariosInterview Q&APremiumSoon

Concurrency coding problems

Classic problems you may be asked to code live.

Concurrency coding problemsPractice problemsPremiumSoon
Concurrency coding problems: interview questions & scenariosInterview Q&APremiumSoon

Finish the module

Module interview question bank

Every interview question worth practising for Multithreading & Concurrency, 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