Pry

🔭 An Erlang application for observing supervision trees

As of right now, pry is just a very simple application that will trace and store all of erlang:spawn and erlang:spawn_link calls being made for any non-standard Erlang module.

Have a look at pry_blacklist to see exactly what's being ignored.

Installation

Simply include in your rebar.config as:

{deps, [
  % ...
  {pry, {git, "https://github.com/ostera/pry", {tag, "0.1.0"}}}
  % ...
]}.

Usage

Include pry in your application start up list, before your actual application, so it'll start tracking everything.

Shell Sesssion Tutorial

Eshell V7.3  (abort with ^G)
1> application:start(pry).
ok
2> pry:add_publisher(self()).
ok
3> application:start(schrodinger).
ok
4> flush().
Shell got #{info => [{registered_name,schrodinger_sup},
             {current_function,{gen_server,loop,6}},
             {initial_call,{proc_lib,init_p,5}},
             {status,waiting},
             {message_queue_len,0},
             {messages,[]},
             {links,[<0.86.0>,<0.88.0>]},
             {dictionary,[{'$ancestors',[<0.86.0>]},
                          {'$initial_call',{supervisor,schrodinger_sup,1}}]},
             {trap_exit,true},
             {error_handler,error_handler},
             {priority,normal},
             {group_leader,<0.85.0>},
             {total_heap_size,233},
             {heap_size,233},
             {stack_size,9},
             {reductions,104},
             {garbage_collection,[{min_bin_vheap_size,46422},
                                  {min_heap_size,233},
                                  {fullsweep_after,65535},
                                  {minor_gcs,0}]},
             {suspending,[]}],
            mfa => {schrodinger_sup,start_link,0},
            parent => <0.86.0>,
            self => <0.87.0>,
            timestamp => {1465,643365,584223}}
Shell got #{info => [{registered_name,schrodinger_lab},
             {current_function,{gen_server,loop,6}},
             {initial_call,{proc_lib,init_p,5}},
             {status,waiting},
             {message_queue_len,0},
             {messages,[]},
             {links,[<0.87.0>]},
             {dictionary,[{'$ancestors',[schrodinger_sup,<0.86.0>]},
                          {'$initial_call',{schrodinger_lab,init,1}}]},
             {trap_exit,false},
             {error_handler,error_handler},
             {priority,normal},
             {group_leader,<0.85.0>},
             {total_heap_size,233},
             {heap_size,233},
             {stack_size,9},
             {reductions,20},
             {garbage_collection,[{min_bin_vheap_size,46422},
                                  {min_heap_size,233},
                                  {fullsweep_after,65535},
                                  {minor_gcs,0}]},
             {suspending,[]}],
            mfa => {schrodinger_lab,init,1},
            parent => <0.87.0>,
            self => <0.88.0>,
            timestamp => {1465,643365,584277}}
ok

Event format

#{
  % Raw Process information
  info => [{current_function,{pry,dummy,1}}, ..],

  % Quick access to the MFA this process was spawned with
  mfa => {pry,dummy,1},

  % Pid of the parent
  parent => <0.77.0>,

  % Pid of this process
  self => <0.79.0>,

  % Timestamp when the tracer sent this process for tracking
  timestamp => {1465,43729,784546}
}

Motivation

Inspired by Ruby's pry, I set forth to make a tool that would collect, format, and export as much information of the running process trees as they were being created and destroyed.

The goal of pry is to be a drop-in tool to get an exploratory view of your running erlang system.

Contributing

Fork, make a topic branch, and send a Pull Request. Travis will let you know if it's good to go, and from the on we can review, retouch, and merge.

Included here is a Makefile with handy targets. Run make to execute the complete battery of tests.

Next Steps

See the issues page for a list of planned enhancements and features.

License

See LICENSE.