Routemap source tree

lispking edited this page May 22, 2014 · 20 revisions

Erlang OTP is a complex system. It can be a bit hard to find out where to look if you want to know the details of some implementation. This page is a simple routemap to the interesting parts of the Erlang OTP source code. With ‘interesting’ I mean for users who are interested in the internal workings of Erlang for example for performance reasons and networking.


Erlang Run-Time System Application.This tree includes the virtual machine, the garbage collector, and the port mapper daemon. The documentation about ERTS shows that erl_driver, erl_nif, zlib, epmd, erl and erlang all belong to this basic application.


Erlang’s Beam VM: contains .c and .h files such as:

  1. erl_process.c,
  2. beam_emu.c,
  3. binary.c, The implementation of Erlang binaries (doc)
  4. erl_driver.h, Erlang drivers header, much more information in the docs
  5. io.c,
  6. bif.c the C implementations for builtin functions in the ‘erlang’ module (doc). It contains for example implementations of erlang:spawn() or erlang:link()
  7. erl_bif_port.c,
  8. erl_alloc.c (doc)
  9. erl_nif.c (doc) – The coolest addition to the R13B03 release, Native Implemented Functions!


  1. inet_drv.c


Erlang’s native code compiler. Interaction between Beam and Native code

  1. ‘Secret’ erlang functions for destructive array operations.


Contains the Erlang libraries. That means: lots of files written in Erlang code to implement lots of functions you use every day.


  1. application.erl
  2. gen_tcp.erl
  3. heart.erl
  4. inet.erl


  1. array.erl,
  2. dict.erl,
  3. gb_trees.erl
  4. lists.erl
  5. string.erl
  6. ets.erl,
  7. gen_server.erl
  8. gen_fsm.erl
  9. gen_event.erl
  10. io.erl,
  11. timer.erl,
  12. unicode.erl
  13. beam_lib.erl

Note: feel free to edit and point out more interesting parts of the source code.