WhatsApp is achieving ~3M concurrent connections on a single node. [1][2]
The architecture is FreeBSD and Erlang.
It does make me wonder, and I've asked this question before [3], why can WhatsApp handle so much load per node when Twitter struggled for so many years (e.g. Fail Whale)?
The problem of 1:1 messaging is slightly different to Twitter, which is more m:n. 1:1 messaging can be handled reasonably easily with a mailbox per user, and there is no shared state. Messaging with m:n has different optimal patterns depending on the relative ratios of m and n. Twitter has many users with millions of followers; if Twitter used a 1:1 mailbox approach like a chat app, these users would be whole countries worth of load on their own.
That's not to say that Twitter's scaling issues where wholly forgivable. They weren't fatal to the service, but I don't think they were necessary with good design from the start. High popularity is a good problem to have though.
Haven't you answered your own question? FreeBSD + Erlang vs Rails. Not hating on Rails but it wasn't remotely designed for this use case, Erlang was and there's arguably nothing better in the world at it. Twitter got better after they moved to the JVM, another battle-hardened platform designed for scale.
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WhatsApp is achieving ~3M concurrent connections on a single node. [1][2]
The architecture is FreeBSD and Erlang.
It does make me wonder, and I've asked this question before [3], why can WhatsApp handle so much load per node when Twitter struggled for so many years (e.g. Fail Whale)?
[1] http://blog.whatsapp.com/index.php/2012/01/1-million-is-so-2...
[2, slide 16] http://www.erlang-factory.com/upload/presentations/558/efsf2...
[3] https://news.ycombinator.com/item?id=7171613
The problem of 1:1 messaging is slightly different to Twitter, which is more m:n. 1:1 messaging can be handled reasonably easily with a mailbox per user, and there is no shared state. Messaging with m:n has different optimal patterns depending on the relative ratios of m and n. Twitter has many users with millions of followers; if Twitter used a 1:1 mailbox approach like a chat app, these users would be whole countries worth of load on their own.
That's not to say that Twitter's scaling issues where wholly forgivable. They weren't fatal to the service, but I don't think they were necessary with good design from the start. High popularity is a good problem to have though.
Haven't you answered your own question? FreeBSD + Erlang vs Rails. Not hating on Rails but it wasn't remotely designed for this use case, Erlang was and there's arguably nothing better in the world at it. Twitter got better after they moved to the JVM, another battle-hardened platform designed for scale.