Question

Can any one guide me with example about Thread and ThreadPool what is difference between them? which is best to use…? what are the drawback on its

Answer 1

Since a thread can only run once, you’d have to use a thread per task. However, creating and starting threads is somewhat expensive and can lead to a situation where too many threads are waiting for execution (don’t remember the exact name for this right now) – which further reduces performance.

A thread pool is – as the name suggests – a pool of worker threads which are always running. Those threads then normally take tasks from a list, execute them, then try to take the next task. If there’s no task, the thread will wait.

Using a thread pool has several advantages:

• you don’t have to create a thread per task
• you normally have the optimal number of threads for your system (depending on the JVM too)
• you can concentrate on writing tasks and use the thread pool to manage the infrastructure

Edit: Here are some quite good articles on concurrency in general: Sutter’s Mill, look at the bottom for more links. Although they’re primarily written for C/C++ the general concepts are the same, since it also describes the interdependence between concurrency solutions and hardware. A good article to understand concurrency performance issues is this article on drdobbs.com.