I have a method void DoWork(object input) that takes roughly 5 seconds to complete. I have read that Thread is better suited than ThreadPool for these longer operations but I have encountered a problem.
I click a button which calls threadRun.Start(input) which runs and completes fine. I click the button again and receive the following exception:
Thread is running or terminated; it cannot restart.
Can you not “reuse” a Thread? Should I use ThreadPool? Why is Thread “better suited for longer operations” compared to ThreadPool? If you can’t reuse a thread, why use it at all (i.e. what advantages does it offer)?
You can. But you have to code the thread not to terminate but to instead wait for more work. That’s what a thread pool does.
If you want to re-use a thread, yes.
Imagine a thread pool that is serving a large number of quick operations. You don’t want to have too many threads, because the computer can only do so many things at a time. Each long operation you make the thread pool do ties up a thread from the pool. So the pool either has to have lots of extra threads or may run short of threads. Neither leads to an efficient thread pool design.
For longer operations, the overhead of creating and destroying a thread is very small in comparison to the cost of the operation. So the normal downside of using a thread just for the operation doesn’t apply.
I’m assuming you mean using a thread dedicated to a job that then terminates over using a thread pool. The advantage is that the number of threads will always equal the number of jobs this way. This means you have to create a thread every time you start a job and destroy a thread every time you finish one, but you never have extra threads nor do you ever run short on threads. (This can be a good thing with I/O bound threads but can be a bad thing if most threads are CPU bound most of the time.)