Threading a large amount of threads

So I loop that will loop about 20000 times. Each time it loops, I create a new thread. The thread basically calls one method. The method is rather slow it takes four seconds to complete. It goes out and scrapes some page(which we开发者_JAVA百科 have permission to scrape). I add a one second delay in the loop which would make sure only 4 pages are being scrapped at once. My question what happens to that thread once the method is completed?

Thread.Sleep(1000);
Thread t = new Thread(() => scraping(asin.Trim(), sku.Trim()));
t.Start();

My question what happens to that thread once the method is completed?

It will get destroyed as soon as the method completes.

That being said, this is not an ideal approach. You should use the ThreadPool to avoid creating many threads.

Instead of using new Thread, consider using ThreadPool.QueueUserWorkItem to start off the task.

In addition, if you're using .NET 4, you can use Parallel.ForEach to loop through your entire collection concurrently. This will use the ThreadPool (by default) to schedule all of your tasks.

Finally, you probably should eliminate the Thread.Sleep in your loop - it will just slow down the overall operation, and probably not provide you any gains (once you've switched to using the ThreadPool).

It exits and gets destroyed. Maybe you'd be more interested in using a ThreadPool instead and set their maximum thread count to 4?

It will reuse the same threads for doing your task, as constructing new threads involves allocating new memory for their stacks, especially if you're doing that 20000 times, it might be one of your bottlenecks.

It gets collected and discarded by the operating system. You might be better off with ThreadPool.QueueUserWorkItem. This will re-use threads so you don't have to incur the setup/teardown cost 20000 times.

Based on your edited post, the thread will be destroyed and its resources garbage collected. As @Karim has also mentioned.

If you were using a ThreadPool it would be returned to the pool. If you know exactly how many threads you plan to keep active at any given time you could create a pool with that number to save some overhead.