ferd

-spec gc_count(non_neg_integer(), binary()) -> non_neg_integer().
gc_count(PreviousCounter, Bin) ->
    case byte_size(Bin) of
        N when N >= 64 -> % refc binary
            Count = N + PreviousCounter
            case Count >= ?THRESHOLD of
                true ->
                    erlang:garbage_collect(),
                    0;
               false ->

ferd

#!/usr/bin/env awk -f
BEGIN {
# crash dump separators
    FS=":"
# states
    proc=1 # in a proc_heap or proc_stack
    binary=2 # after the proc_heap or proc_stack
    memory=3 # memory printing area
    state=0
    min=100

ferd

f(MostLeaky).
MostLeaky = fun(N) ->
    lists:sublist(
     lists:usort(
         fun({K1,V1},{K2,V2}) -> {V1,K1} =< {V2,K2} end,
         [try
              {_,Pre} = erlang:process_info(Pid, binary),
              erlang:garbage_collect(Pid),
              {_,Post} = erlang:process_info(Pid, binary),
              {Pid, length(Post)-length(Pre)}

ferd

f(Percentiles).
Percentiles = fun(Numbers) ->
    Percentile = fun(List, Size, Perc) ->
        Element = round(Perc * Size),
        lists:nth(Element, List)
    end,
    Len = length(Numbers),
    Sorted = lists:sort(Numbers),
    [{trunc(Perc*100), Percentile(Sorted, Len, Perc)} ||
        Perc <- [0.50, 0.75, 0.90, 0.95, 0.99, 0.999]]

ferd

%% Convert a crashdump binary back into a regular binary
%% Crash dump binary:
%% =binary:CFE75808  % <- reference to refc binary
%% CA:2A31300D0A24350D0A484D5345540D0...  % <- actual binary
CDumpBin = fun(Str) ->
  [Len,Num] = string:tokens(Str, ":"),
  Src= lists:flatten(["<<16#",Num,":(16#",Len,"*8)>>."]),
  {ok, Tokens, _}=erl_scan:string(Src),
  {ok, [Form]} = erl_parse:parse_exprs(Tokens),
  {value, Val, _} = erl_eval:expr(Form, erl_eval:new_bindings()),

ferd

λ self → git clone git@github.com:ferd/vmstats.git
Cloning into 'vmstats'...
Identity added: /Users/ferd/.ssh/id_rsa (/Users/ferd/.ssh/id_rsa)
remote: Counting objects: 83, done.
remote: Compressing objects: 100% (65/65), done.
remote: Total 83 (delta 44), reused 57 (delta 18)
Receiving objects: 100% (83/83), 113.39 KiB, done.
Resolving deltas: 100% (44/44), done.
λ self → cd vmstats
λ vmstats → master → ls

ferd

erlang:system_flag(scheduler_wall_time, true),
f(WallTimeDiff),
WallTimeDiff = fun(T1,T2) -> [trunc(100*((Active2-Active1)/(Total2-Total1)))/100 || {{I, Active1, Total1}, {I, Active2, Total2}} <- lists:zip(lists:sort(T1),lists:sort(T2))] end,                                                                                                                                        
f(F), put(stime, erlang:statistics(scheduler_wall_time)), 
F = fun(F,N) -> Old=get(stime), New=erlang:statistics(scheduler_wall_time), put(stime,New), io:format("rt:~p\trq:~p\t\tsched:~w~n", [element(2,erlang:statistics(runtime)), erlang:statistics(run_queue), WallTimeDiff(Old,New)]), timer:sleep(N), F(F,N) end.

%% F(F, IntervalInMS).

ferd

f(Init), f(Loop), f(Stats), f(ShowStats),
Init = fun(Delay) ->
  Ref = erlang:start_timer(Delay, self(), '#delay'),
  {{input,In},{output,Out}} = erlang:statistics(io),
  PrevGC = erlang:statistics(garbage_collection),
  {{Delay,Ref}, {In,Out}, PrevGC}
end,
Loop = fun(Self,F,N,{{D,R},{OldIn,OldOut},{OldGCs,OldWords,_}}) ->
  receive
    {timeout,R,'#delay'} ->

ferd

f(Window).

Window = fun(AttrName, Time,NumProcs) ->
 Attrs = fun(Name) ->
      [{Pid, {Attr, Curr, Init}}
       || Pid <- processes() -- [self()],
          [{_, Attr}, {_, Curr}, {_, Init}] <-
             [process_info(Pid, [Name, current_function, initial_call])]]
 end,
 F = fun() -> Attrs(AttrName) end,

ferd

-module(behaviour_parse).
-export([parse_transform/2]).
-define(CUTOFF, "2.15"). % R15B

parse_transform(AST, _Opts) ->
    [Vsn] = [X || {kernel,_,X} <- application:which_applications()],
    walk_ast(if Vsn >= ?CUTOFF -> spec;
                Vsn < ?CUTOFF -> func
             end,
             AST).