ERLANGEN: ASYNCHRONOUS, DISTRIBUTED MESSAGE PASSING
                        FOR CLOZURE CL (LIGHTNING TALK FOR ELS 2017)

                                             Max Rottenkolber <max@mr.gy>
                                                    Tuesday, 4 April 2017

Erlangen

 * asynchronous message passing

 * reliable (supervision trees)

 * inherently distributed

 * inspired by Erlang, yet very different

“You can’t do that, it won’t be like Erlang!”

 * uses native OS threads (can’t have 10,000)

 * does not enforce strict isolation (within the boundary of a node)

 * Common Lisp is synchronous (blocking I/O)

   …there are also many reasons to prefer CL/Erlangen over Erlang

 * for instance, Erlangen’s message queues are bounded and never leak
   memory

I did it, its amazing: lessons learned

 * uses native OS threads

   even if processes are heavy, supervision trees are worth their weight
   in gold

 * does not enforce strict isolation

   just don’t modify objects you send (send = free)

 * Common Lisp is synchronous (blocking I/O)

   tempted to look at asynchronous I/O (IOLib): complete dead end, no
   tasteful way to write code

   blocking is fine as long as you always supply a timeout

Write reliable services in Common Lisp

     URI: erlangen-els-2017-lightning-talk-supervision-tree.svg

       Supervision tree of a real-life application (processes can be
       spread on remote nodes)

Research: explore distributed designs

     URI: erlangen-explore-kademlia-dht-merge1.svg

       live visualization of 300 SLOC Kademlia DHT implementation on
       Erlangen

Numbers (on Intel Xeon E31245 3.30GHz)

 * 5us for message delivery, 10x more than erts 7.3 (that’s not even
   bad, actually)

 * up to 2 million messages per second

 * you can have 1,000 processes easily

   …no serious optimization work done so far!

No SBCL, … support because

 * portability layers are boring

 * portability layers are boring

 * portability layers are boring

 * I won’t write one or maintain one

 * Erlangen already includes modifications to CCL

 * …maybe I want to swap out CCL’s threading, GC, I/O, …
   implementations?

 * erlangen-kernel is distributed as an executable that includes
   Quicklisp

Hack it!

 * github.com/eugeneia/erlangen AGPL-3.0

 * branch, fork all you like

 * nothing is set in stone yet, wild ideas welcome

 * mail me at max@mr.gy

     URI: ../site-assets/inters-centered.svg