Shahzad Bhatti Welcome to my ramblings and rants!

I just read “Let It Crash” Programming, which talks about how Erlang is designed as a fault tolerant language from ground up. I have been learning Erlang since Joe Armstrong’s book came out and have heard Joe a few times talk about fault tolerance. Steve Vionski has also talked about Erlang: It.s About Reliability in flame war between him and Ted Neward. For me, Erlang reminds of Microsoft Windows, i.e. when Windows stops working I just reboot the machine. Erlang does the same thing, when some process fails, it just restarts the processes. About sixteen years ago, I started my career in old VAX, Mainframe and UNIX environments and my managers used to say that he never had to restart Mainframe if something fails, but somehow bugs on Windows get fixed after reboot. When I worked at Fermilab in mid 90s, we had server farms of hundreds of machines and fault tolerance was quite important. Though, Google didn’t invent server farms, but it scaled them to new level, where failure of machines don’t stop the entire application. Erlang takes the same philosophy to the programming language. Obviously, in order to make truly fault tolerant application, the Erlang processes will need to be spawned on separate machines. Erlang’s support of CSP style communication and distributed computing such as OTP makes it trivial. You can further increase fault tolerance and high availibility by using machines on separate racks, networks, power sources or data centers. No wonder, Facebook is using Erlang in its Chat application.