Are there any disadvantages of using a thread pool?

Question

I know the thread pool is a good thing because it can reuse threads and thus save the cost of creating new threads. But my question is, are there any disadvantages of using a thread pool? In which situation is using a thread pool not as good as using just individual threads?

Answer 1

In which situation is using a thread pool not as good as using just individual threads?

The only time I can think of is when you have a single thread that only needs to do a single task for the life of your program. Something like a background thread attached to a permanent cache or something. That's about the only time I fork a thread directly as opposed to using an ExecutorService. Even then, using a Executor.newSingleThreadExecutor() would be fine. The overhead of the thread-pool itself is maybe a bit more logic and some memory but very hard to see a pressing downside.

Certainly anytime you need multiple threads to perform tasks, a thread-pool is warranted. What the ExecutorService code does is reduce the amount of code you need to write to manage the threads. The improvements in readability and code maintainability is a big win.

Answer 2

Threadpool is suitable only when you use it for operations that takes less time to complete. Threadpool threads are not suitable for long running operations, as it can easily lead to thread starvation.

If you require your thread to have a specific priority, then threadpool thread is not suitable.

You have tasks that cause the thread to block for long periods of time. The thread pool has a maximum number of threads, so a large number of blocked thread pool threads might prevent tasks from starting.