Learning paths

Multithreading: beginner to advanced

Start with what a thread is, then learn why shared data breaks and how to protect it, then the tools real systems use: thread pools, CompletableFuture, concurrent collections and virtual threads.

  • For: You know basic Java and want to understand threads properly, step by step.
  • By the end: You can write correct concurrent code, explain race conditions and deadlocks, and answer multithreading interview questions confidently.
  • Size: 8 lessons (35 min of reading, plus time to try the code), beginner to advanced
Start with Multithreading basics: threads, Runnable and Callable
  1. Race conditions and synchronization: synchronized, locks, volatile and atomicsConcurrency and the JVM, intermediate, 5 min
  2. ExecutorService, ThreadPoolExecutor and FutureConcurrency and the JVM, advanced, 6 min
  3. Concurrent collections and synchronizers: ConcurrentHashMap, CountDownLatch, CyclicBarrier and SemaphoreConcurrency and the JVM, advanced, 5 min
  4. CompletableFutureConcurrency and the JVM, advanced, 3 min
  5. Virtual threadsConcurrency and the JVM, advanced, 3 min
  6. HashMap vs ConcurrentHashMapCollections compared, advanced, 3 min
  7. Fail-fast vs fail-safe iteratorsCollections compared, intermediate, 3 min

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