Today I Learned

A Hashrocket project

Get pids for each beam application in Elixir

In Elixir, it’s hard to determine what pids belong to what applications just by using Process.info

iex> pid(0,45,0) |> Process.info
[
  current_function: {:application_master, :main_loop, 2},
  initial_call: {:proc_lib, :init_p, 5},
  status: :waiting,
  message_queue_len: 0,
  links: [#PID<0.46.0>, #PID<0.43.0>],
  dictionary: [
    "$ancestors": [#PID<0.44.0>],
    "$initial_call": {:application_master, :init, 4}
  ],
  trap_exit: true,
  error_handler: :error_handler,
  priority: :normal,
  group_leader: #PID<0.45.0>,
  total_heap_size: 376,
  heap_size: 376,
  stack_size: 7,
  reductions: 49,
  garbage_collection: [
    max_heap_size: %{error_logger: true, kill: true, size: 0},
    min_bin_vheap_size: 46422,
    min_heap_size: 233,
    fullsweep_after: 65535,
    minor_gcs: 0
  ],
  suspending: []
]

With the above output, I can’t tell what application this is!

I can use the :running key of Erlang’s :application.info to get a map of applications to pids.

iex> :application.info[:running]
[
  logger: #PID<0.93.0>,
  iex: #PID<0.85.0>,
  elixir: #PID<0.79.0>,
  compiler: :undefined,
  stdlib: :undefined,
  kernel: #PID<0.45.0>
]

Oh ok, pid(0,45,0) is the Kernel application.

Looking for help? Elixir is quickly gaining momentum for web applications that need concurrency, performance, and the ability to connect to many different clients. The developers at Hashrocket are learning along with the rest of the development community that Elixir and Phoenix are viable Rails alternatives for the right application. Check out the source code for Today I Learned, written in Elixir, and contact us if you need help with your Elixir project.