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Concurrency

Concurrency practice

Race conditions

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Two threads each run count++ 100,000 times on a shared int, with no lock. Final count?

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Threads, async, locks, and the hazards

Master the concurrency programming model — concurrency vs parallelism, threads vs processes, async/await and the event loop, synchronization (mutex, semaphore, monitor, condition variables), the hazards (race conditions, deadlock and its four conditions, livelock, starvation), atomicity and lock-free techniques (CAS), and the memory model (visibility, happens-before, false sharing). Cross-language and evergreen. Part of the Developer track.

• Meets you at your level — never too easy, never too hard.

• Adapts every question to how you’re doing.

• Tracks your level over time. Skill practice, not a test.

New here? Read the Concurrency guide

A free 16-minute primer — the mental model, the mistakes beginners make, and what to practice first.

Curriculum

217 concepts across 22 chapters, from foundations through advanced practice — each one a concept the adaptive question bank can teach and test.

A. Concurrency, parallelism and units of execution

B. Shared state, race conditions and data races

C. Atomicity, visibility and ordering

D. Happens-before and what a memory model promises

E. The Go memory model's synchronization edges

F. Java's memory model and threading contract

G. C++ memory_order and fences

H. Mutual exclusion and lock design

I. Deadlock, livelock, starvation and priority

J. Condition variables and waiting

K. Semaphores, latches and barriers

L. Atomics, CAS and non-blocking progress

M. Caches, coherence and the cost of sharing

N. Concurrent data structures and safe reclamation

O. Thread pools, executors and work stealing

P. Futures, promises and async composition

Q. Coroutines, async/await and event loops

R. Channels, CSP and actors

S. Cancellation and structured concurrency

T. Immutability, confinement and safe publication

U. Classic bugs and how they are actually found

V. Consistency and progress models

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Concurrency on exams

Concurrency is one of the skills tested on these exams. Each prep page lays out what the real test covers and where this skill fits.

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