如何立即杀死正在等待网络操作的线程？

So, I'm creating a download manager, and I've designed every bit specifically so that it can be shut down at any second without giving it the time to clean up. However, I can't seem to find a way to kill my downloader threads. I tried using Thread.Abort (actually, that's my way of giving them time to clean up: they catch the ThreadAbortException and handle it themselves), but as you can already guess, it's no good. I'd use a flag or something, but when a thread is waiting for a network operation to complete, it's pretty much blocked completely. Any ideas on how to at least interrupt the network operation so I can shut down without waiting a noticeable amount of time?So, I'm creating a download manager, and I've d