Brewlearn Get the app
World 20 of 26 · Advanced

⚡ Advanced Concurrency

14 Java concepts, each explained step by step with real code, a common trap and practice questions.

  1. ExecutorService & thread poolsFixed, cached, scheduled pools; submit vs execute; shutdown.
  2. Callable & FutureReturning results, get() blocks, cancel, ExecutionException.
  3. CompletableFuturesupplyAsync, thenApply, thenCompose, thenCombine, allOf, exceptionally.
  4. Atomic classes & CASAtomicInteger, compare-and-set, LongAdder under contention.
  5. ReentrantLock & ConditiontryLock, fairness, lockInterruptibly, always unlock in finally.
  6. ReadWriteLock & StampedLockMany readers or one writer; optimistic reads.
  7. ConcurrentHashMapThread-safe map, atomic compute/merge, no null keys or values.
  8. Other concurrent collectionsCopyOnWriteArrayList, ConcurrentLinkedQueue, BlockingQueue producer-consumer.
  9. SynchronizersCountDownLatch, CyclicBarrier, Semaphore, Phaser.
  10. Fork/Join frameworkDivide and conquer with RecursiveTask and work stealing.
  11. Virtual threadsJava 21 lightweight threads for blocking I/O at massive scale; pinning; don't pool them.
  12. Structured concurrencyStructuredTaskScope (preview): treating related tasks as one unit.
  13. Scoped valuesJava 25 ScopedValue as an immutable, bounded alternative to ThreadLocal.
  14. Sizing thread poolsCPU-bound vs I/O-bound work, rejection policies, bounded queues.