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concurrency

Thread Pool

A thread pool maintains a set of pre-created worker threads that pick up tasks from a shared queue. Instead of creating and destroying a thread for every task (which is expensive), the pool reuses existing threads. This reduces overhead, limits resource consumption, and provides natural backpressure when the pool is saturated. Thread pools are the standard execution model for web servers, database connection handlers, and parallel processing frameworks.

Use Cases

  • Web servers handling incoming HTTP requests with a fixed number of worker threads
  • Parallel file processing where each worker handles one file at a time
  • Database query execution with a bounded connection pool
  • Background job processing systems like Celery or Sidekiq

Visualization

INITIALTask QueueT1T2T3T4T5CompletedWorker 1idleWorker 2idleWorker 3idle
Speed:1x
A thread pool with 3 workers processes a queue of 5 tasks.Step 1 / 6

Implementation

Output

Click "Run Code" to see output...