How Thread Life Cycle works inside Thread Pool?

Question

Could anyone explain how thread life cycle works inside thread pool.Is it same as normal thread life cycle?

Answer 1

1. ThreadPool can wrap your Runnable/Callable with Future*(if you use submit() method)
2. Runnable/Callable faces with task queue and saturation policy
   • behaviour depends on:
     • number of active threads in pool
     • corePoolSize
     • maximumPoolSize
     • saturation of queue
     • saturation policy(default is AbortPolicy)
3. ThreadFactory creates Thread. Can be configured:
   • set UncaughtExceptionHandler
   • set name of Thread
   • set daemon flag
4. beforeExecute() - empty hook method, you can override it
5. Running your Thread
6. afterExecute()** - empty hook method, you can override it
7. Thread may be terminated or waits for processing new task. Configured by allowCoreThreadTimeOut()

* using submit() method changes code for afterExecute() - Handling exceptions from Java ExecutorService tasks
**afterExecute() will be not invoked if beforeExecute() throw any Exception

Note: part of behaviour of thread pool is similar to pattern template method - beforeExecute() -> run() -> afterExecute().