Concurrency Patterns

Overview

Concurrency patterns provide standard structures and templates to solve common multi-threaded challenges: - Signaling: One thread notifying another about state changes. - Thread Pool: Reusing a fixed pool of threads to execute asynchronous tasks, avoiding thread creation overhead. - Producer-Consumer: Separating work creation from work execution using a blocking queue. - Reader-Writer: Allowing multiple concurrent readers but exclusive writer access to a resource.

Key Concepts

• Signaling Pattern: Uses wait()/notify() or Semaphores to coordinate dependencies between thread steps.
• Thread Pool Pattern: Comprises a task queue and worker threads. Configured with core pool size, max pool size, and queue capacity.
• Producer-Consumer Pattern: Decouples components. Producers push tasks, consumers pull tasks. Handles spikes naturally via queue buffering.
• Reader-Writer Pattern: Implements ReentrantReadWriteLock. Multiple threads read concurrently; if a thread wants to write, it blocks all readers and other writers.

Best Practices

• Always use bounded queues in Producer-Consumer systems to prevent OutOfMemoryErrors under high load.
• Use standard ExecutorService thread pools instead of manually creating threads.

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