Java concurrency and locks
Free Java concurrency module: threads, locks, race conditions, and ConcurrentHashMap under load. First topics open in the browser — no sign-up.
Free Core Java module on threads, locks, race conditions, and what breaks under load. Open the first topics in the browser — no account.
Backend interviews still start with concurrency: shared mutable state, synchronized vs Lock, ConcurrentHashMap, and why a race is not “just add volatile”. This guest module is the same concurrency track paid users study, with the first topics unlocked.
Use it before the production labs. The HikariCP leak and RestTemplate hang are concurrency-adjacent: threads blocked on a pool or a socket. The module explains the language primitives; the labs show those primitives failing in Spring.
What you will cover
- Threads, runnables, and executor pools
- synchronized, ReentrantLock, and deadlock
- Race conditions vs visibility (volatile, happens-before)
- Concurrent collections under write load
- First topics free; remaining topics after sign-in
Related free labs and modules
Common questions
Is there a free Java concurrency tutorial here?
Yes. The Java concurrency module opens without an account. You get the first topics on threads, locks, and races. Sign in to continue the rest of the module and save progress.
How is this different from a HikariCP debug lab?
The module teaches Java concurrency primitives. The HikariCP lab is a Spring production incident caused by leaked connections under concurrent load. Do both: language first, then the incident.
Do I need to sign up to start?
No. The guest preview is a static page. Create an account when you want the full Java track, mocks, and Engineering Hub.
Free Spring Boot debug challenges · Free debug challenges · Java Spring Boot path · Create free account