This is a sample project that illustrates some strange behavior I ran into trying to upload files to Amazon S3 using EventMachine and the happening non-blocking S3 client.
You need to update the s3.yml file with your S3 account information and run bundle install. Then you can run either of the two included scripts:
ruby lib/http_upload.rb
or
ruby lib/https_upload.rb
On my machine (Mac OS X) when I run the https script the CPU spikes to 100% and the event loop is blocked for a couple of minutes before the file starts to transfer. However, the http version does not block the event loop, uses almost no CPU, and starts transferring data right away.