Edit MultiThreaded Ruby Script for Downloading Webpages

I want to make a script which reads from a file of URLs and downloads all the text from all the web pages, and puts them into a big file in a folder called results. I want this to be multithreaded supporting at least 100 threads. I have some code, such as the code to read the URL text document, but need help with the multithreading and parsing the text from the web pages. Both HTTPS and HTTP sites must be supported, and this will need to be able to support thousands or million of URLs.