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Increasing max_size significantly degrades performance. #55

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jhlywa opened this Issue Nov 27, 2012 · 1 comment

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jhlywa commented Nov 27, 2012

Here's a simple contrived example:

-module(perf_ex).                                                                  
-compile(export_all).                                                              
-include_lib("proper/include/proper.hrl").                                         

-record(msg, {                                                                     
  a = 0 :: 0..16#ffffffff,                                                         
  b = 0 :: 0..16#f                                                                 
}).                                                                                
-type(msg() :: #msg{}).                                                            

-spec encode(msg()) -> binary().                                                   
encode(#msg{a = A, b = B}) -> <<A:32, B:4>>.                                       

-spec decode(binary()) -> msg().                                                   
decode(<<A:32, B:4>>) -> #msg{a=A, b=B}.                                           

prop_identity() -> ?FORALL(Msg, msg(), Msg =:= decode(encode(Msg))).               

And the results:

1> timer:tc(fun() -> proper:quickcheck(perf_ex:prop_identity(), [5, {max_size, 42}]) end).
.....                                                                              
OK: Passed 5 test(s).                                                              
{8170,true}                                                                        

2> timer:tc(fun() -> proper:quickcheck(perf_ex:prop_identity(), [5, {max_size, 16#ffffffff}]) end).
.....                                                                           
OK: Passed 5 test(s).                                                              
{658751072,true}                                                                   

I haven't been able to determine what's causing the slowdown, but it's significant. Any suggestions?

@ghost ghost assigned manopapad Feb 26, 2013

@manopapad manopapad closed this in 91aaec3 Mar 30, 2013

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manopapad commented Mar 30, 2013

Thanks for reporting this. The issue should be fixed now, let me know if it's still giving you trouble.

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