Question

The consensus, when it comes to multi-threading & concurrency in Java-land, is to isolate the code you want multi-threaded as a “task” and to submit that task to some kind of executor service or thread pool.

What I’m wondering is:

• Can a task be any method of any object, or does it have to be something special (if so, what)?
• How do you determine whether this task is CPU-, IO-bound or other? What are some “dead giveaways” or other deciding factors?

Thanks in advance for any clarity here!

Answer 1

Take a look at ExecutorService:

• submit(Callable)
• submit(Runnable)

Your task should probably be one of the two interfaces (which can always call other methods).

Your task is probably IO bound if you perform any input/output operations within it: IE, reading to a file, writing to a file, reading from a socket, writing to a socket, etc.