How does maximumPoolSize of ThreadPoolExecutor works?

Question

I\'m trying to understand ThreadPoolExecutor class. I have read this answer and the Javadoc. But my experimentation doesn\'t match with that description:

I initializ

Answer 1

From the API for ThreadPoolExecutor:

If there are more than corePoolSize but less than maximumPoolSize threads running, a new thread will be created only if the queue is full.

Your queue never fills since it has a capacity of 1000. If you change the capacity to 1, you will see Threads being created.

The Executors class uses a SynchronousQueue for its newCachedThreadPool methods, so you might want to consider using it as well.