The problem is not with Async IO. It has all to do with the various Callbacks. If you want to do async things inside those callbacks, you can't with how OpenS

The problem is not with Async IO. It has all to do with the various Callbacks. If you want to do async things inside those callbacks, you can't with how OpenSSL is structured today. Twisted, for exmaple lets you set various options: http://twistedmatrix.com/documents/10.1.0/api/twisted.internet.ssl.CertificateOptions.html http://twistedmatrix.com/documents/10.1.0/api/twisted.intern... This makes it so the actual callbacks are just checking variables to make their decisions, but you can't implement a session cache backend for example in twisted, you are pretty much stuck with the built-in openssl one, for a single process.