Erlang: An introduction to gen_fsm by creating an ATM (Part 2)

http://spawnlink.com/articles/an-introduction-to-gen_fsm-erlybanks-atm/

by mitchellh • 18 years ago

26 8 18 years ago

truebosko• 18 years ago

I think this article and the one before it is great, but I have a hard time understanding real world usage with Erlang.

I know Facebook chat and other high-scale applications were done with Erlang but apart from that, how is it useful over say Python for more simpler applications and systems?

mitchellh4• 18 years ago

Erlang is useful for writing concurrent, high availability systems. If you're writing a simple script to grep a directory and delete a few files or something, a scripting language like Python is fine. If you're writing a basic blog even, I'd say a scripting language like Python is the way to go.

But if you're writing a service like a database where there must be a lot of concurrent connections, Erlang has the feel of a high-level scripting languages, while being a compiled byte-code language.

Also, since Erlang processes are so lightweight and can run across multiple cores, it scales nicely with new CPUs coming out. So, usually without changing any of your code, as 4, 8, 16 core CPUs come out, your Erlang script should theoretically run 4x, 8x, and 16x faster, respectively.

hassy3• 18 years ago

> So, usually without changing any of your code, as 4, 8, 16 core CPUs come out, your Erlang script should theoretically run 4x, 8x, and 16x faster, respectively.

You might want to read this: http://en.wikipedia.org/wiki/Amdahl's_law

The program would have to be 100% CPU-bound and the problem would have to be inherently parallelizable to see Nx speedup with N times as much CPU resource.

The kind of code that benefits most from more cores is the kind of code you probably should not write in Erlang actually.

Erlang: An introduction to gen_fsm by creating an ATM (Part 2)

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