This has been posted twice before[1][2]. It should be noted that this benchmark was done over localhost, i.e. packets did not actually leave the computer, so who knows what kind of optimizations were done by the kernel / networking stack.<p>When looking at examples where packets actually leave the computer, at least one person achieved 1M concurrent connections with Erlang in 2008, and WhatsApp were hitting 2.8M concurrent connections with Erlang in a production system in 2012[4]. Of course memory usage was a lot higher in these examples, but at least they were exercising the networking stack.<p>[1]: <a href="https://news.ycombinator.com/item?id=5127251" rel="nofollow">https://news.ycombinator.com/item?id=5127251</a><p>[2]: <a href="https://news.ycombinator.com/item?id=5474331" rel="nofollow">https://news.ycombinator.com/item?id=5474331</a><p>[3]: <a href="http://www.metabrew.com/article/a-million-user-comet-application-with-mochiweb-part-1" rel="nofollow">http://www.metabrew.com/article/a-million-user-comet-applica...</a><p>[4]: <a href="http://www.erlang-factory.com/upload/presentations/558/efsf2012-whatsapp-scaling.pdf" rel="nofollow">http://www.erlang-factory.com/upload/presentations/558/efsf2...</a>