I will investigate. Can you please post your exact Erlang and Elixir
versions? If you start IEx with "iex" you can see both.



*José Valim*
www.plataformatec.com.br
Skype: jv.ptec
Founder and Director of R&D

On Mon, Jul 4, 2016 at 10:28 AM, Sébastien Varlet <
[email protected]> wrote:

> Hi there,
>
> There is an update to this problem. As explained by @mosic in the
> elixir-forum (
> https://elixirforum.com/t/strange-behavio-u-r-in-my-tests/939/5), the
> timings improve a lot if the prebaked_response module attribute is replaced
> by a context property set by a setup callback.
>
> It is very counterintuitive as I explain in this thread of the
> elixir-forum as module attributes are supposed to be set once at compile
> time. Doing the same in a setup callback means the load is moved from
> compile time to runtime and the JSON file will be read as many times as
> there are tests in the test case.
>
> After applying @mosic's patch, I observed the same significant improvement
> of the test timings.
>
> @mosic and I would really like to understand why.
>
> Le lundi 27 juin 2016 17:27:36 UTC+2, Sébastien Varlet a écrit :
>>
>> Hi Jose,
>>
>> In case it helps, I also ran this test case and watched some surprising
>> results in observer. They are concerning but they still don't tell me
>> what's going on.
>>
>> "If your tests do nothing, do you still get the slowdown?"
>> -> I tried a test "lol" do assert true end, it's fast :)
>>
>> "What if you add a Bypass to a new application?"
>> -> What do you mean ?
>>
>>
>>
>> <https://lh3.googleusercontent.com/-8eWp7fiZtkQ/V3FE-wOy8fI/AAAAAAAAAY4/WQ34yKIs7f8MTPw-8-RCPght1No_SAIywCLcB/s1600/Screen%2BShot%2B2016-06-27%2Bat%2B16.13.44.png>
>>
>>
>> <https://lh3.googleusercontent.com/-DfG0lUOejsQ/V3FFBQ3dNzI/AAAAAAAAAZA/o9d3ieihB6c2SIvul_uviIKsccedql6kgCLcB/s1600/Screen%2BShot%2B2016-06-27%2Bat%2B16.17.24.png>
>>
>>
>> Le lundi 27 juin 2016 16:16:44 UTC+1, José Valim a écrit :
>>>
>>> The next course of action is to try to isolate the error. If your tests
>>> do nothing, do you still get the slowdown? What if you add a Bypass to a
>>> new application? Maybe something is holding the requests on the server? Try
>>> removing or moving components around until you find the minimum sample that
>>> reproduces it.
>>>
>>> On Monday, June 27, 2016, Sébastien Varlet <[email protected]>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> Thanks for your answer.
>>>>
>>>> The Bypass documentation explains that it takes care of shutting down
>>>> what was setup for each test (I guess their macros setup an on_exit
>>>> callback). Also I coded many other tests the exact same way in the same
>>>> codebase and they never caused this problem.
>>>>
>>>> I verified, each test adds its own ~2 seconds not 5 (I have 5 tests
>>>> therefore the test case takes 10 secs).
>>>>
>>>> Also, when I replace the JSON document by a very small one such as:
>>>>
>>>>  @prebaked_response """
>>>>   {
>>>>     "response": {
>>>>       "blog": {},
>>>>       "posts": []
>>>>     }
>>>>   }
>>>>   """
>>>>
>>>> the problem disappears. So if the size of the document is the issue,
>>>> I'm back to square one: is the json decoding taking too long ? apparently
>>>> no since mix test --trace reports a duration for each test between 30ms and
>>>> 200ms. Is the JSON document passed/copied around and it's taking too long ?
>>>> apparently no for the same reason...
>>>>
>>>> I'm really confused here.
>>>>
>>>>
>>>>
>>>>
>>>> Le lundi 27 juin 2016 15:06:00 UTC+1, OvermindDL1 a écrit :
>>>>>
>>>>> I've not seen those cowboy mocking libraries but is it possible that
>>>>> they have to be told to stop somehow, and instead there is maybe a 5s
>>>>> timeout on its process ending after yours ends and maybe another 5s start
>>>>> on the next?  5s is the default and you say 10s so this is the first thing
>>>>> that jumps out at me.  Maybe watch sleeping processes waiting on something
>>>>> during those 2 5s chunks?
>>>>>
>>>>> On Sunday, June 26, 2016 at 9:46:16 AM UTC-6, Sébastien Varlet wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I'm currently working on a client for the Tumblr API. Turns out it's
>>>>>> way more work than anticipated but still a good way to practice.
>>>>>>
>>>>>> However, I'm running at the moment into a problem with a test case
>>>>>> where each test is taking about 2 seconds to run. These tests setup their
>>>>>> own cowboy server (thanks to bypass) in order to simulate the calls. I 
>>>>>> have
>>>>>> written such tests previously and never had this issue.
>>>>>>
>>>>>> This is the file I'm working on:
>>>>>>
>>>>>> https://github.com/svarlet/ex_tumblr/blob/rework_testing_with_bypass/test/ex_tumblr/posts_test.exs#L49
>>>>>>
>>>>>> As you can see, the JSON response is read from a file 'posts.json'
>>>>>> also in the github repo. It is a rather large file (400KB). So my first
>>>>>> suspicion was about the size of the file and the time taken by Poison to
>>>>>> parse it.
>>>>>>
>>>>>> So I used ExProf to verify that:
>>>>>> FUNCTION                                                  CALLS
>>>>>>  %    TIME  [uS / CALLS]
>>>>>> --------                                                  -----
>>>>>>  -------    ----  [----------]
>>>>>> [...]
>>>>>> 'Elixir.Enum':'-reduce/3-fun-1-'/4                          207
>>>>>> 0.03     196  [      0.95]
>>>>>> 'Elixir.ExTumblr.Utils.Parsing':'-to_struct/3-fun-0-'/2     206
>>>>>> 0.04     198  [      0.96]
>>>>>> lists:reverse/1                                             105
>>>>>> 0.04     226  [      2.15]
>>>>>> lists:foldl/3                                               236
>>>>>> 0.04     246  [      1.04]
>>>>>> erlang:binary_to_atom/2                                     206
>>>>>> 0.04     246  [      1.19]
>>>>>> hackney_bstr:'-to_lower/1-lbc$^0/2-0-'/2                    130
>>>>>> 0.05     282  [      2.17]
>>>>>> inet_tcp:recv/3                                             280
>>>>>> 0.05     303  [      1.08]
>>>>>> hackney_tcp_transport:recv/3                                280
>>>>>> 0.05     303  [      1.08]
>>>>>> hackney_http:ce_identity/1                                  280
>>>>>> 0.05     306  [      1.09]
>>>>>> prim_inet:recv/3                                            280
>>>>>> 0.06     311  [      1.11]
>>>>>> prim_inet:recv0/3                                           280
>>>>>> 0.06     320  [      1.14]
>>>>>> hackney_http:content_decode/3                               280
>>>>>> 0.06     321  [      1.15]
>>>>>> 'Elixir.String.Chars':to_string/1                           342
>>>>>> 0.06     322  [      0.94]
>>>>>> 'Elixir.String.Chars.Atom':to_string/1                      342
>>>>>> 0.06     326  [      0.95]
>>>>>> gen_tcp:recv/3                                              280
>>>>>> 0.06     326  [      1.16]
>>>>>> erlang:atom_to_binary/2                                     343
>>>>>> 0.06     333  [      0.97]
>>>>>> hackney_response:stream_body_recv/2                         279
>>>>>> 0.06     340  [      1.22]
>>>>>> 'Elixir.Map':do_take/3                                      363
>>>>>> 0.06     342  [      0.94]
>>>>>> erlang:port_get_data/1                                      282
>>>>>> 0.06     344  [      1.22]
>>>>>> hackney_response:stream_body/2                              279
>>>>>> 0.06     353  [      1.27]
>>>>>> hackney_http:te_identity/2                                  280
>>>>>> 0.06     358  [      1.28]
>>>>>> hackney_http:transfer_decode/2                              280
>>>>>> 0.06     363  [      1.30]
>>>>>> hackney_response:read_body/3                                281
>>>>>> 0.07     382  [      1.36]
>>>>>> maps:'-fold/3-fun-0-'/3                                     207
>>>>>> 0.07     398  [      1.92]
>>>>>> maps:find/2                                                 343
>>>>>> 0.07     402  [      1.17]
>>>>>> hackney_bstr:char_to_lower/1                                115
>>>>>> 0.08     475  [      4.13]
>>>>>> hackney_http:'-parse_body/1-fun-3-'/1                       280
>>>>>> 0.11     608  [      2.17]
>>>>>> 'Elixir.String.Chars':impl_for/1                            342
>>>>>> 0.11     626  [      1.83]
>>>>>> 'Elixir.ExTumblr.Post':'-parse/1-fun-0-'/1                  340
>>>>>> 0.11     632  [      1.86]
>>>>>> 'Elixir.String.Chars':'impl_for!'/1                         342
>>>>>> 0.11     639  [      1.87]
>>>>>> hackney_http:execute/1                                      286
>>>>>> 0.12     652  [      2.28]
>>>>>> 'Elixir.Enum':'-map/2-lists^map/1-0-'/2                     381
>>>>>> 0.12     670  [      1.76]
>>>>>> hackney_http:'-parse_body/1-fun-2-'/2                       280
>>>>>> 0.12     674  [      2.41]
>>>>>> hackney_response:stream_body1/2                             560
>>>>>> 0.12     685  [      1.22]
>>>>>> inet_db:lookup_socket/1                                     282
>>>>>> 0.12     693  [      2.46]
>>>>>> prim_inet:async_recv/3                                      280
>>>>>> 0.12     700  [      2.50]
>>>>>> hackney_response:recv/1                                     280
>>>>>> 0.13     714  [      2.55]
>>>>>> prim_inet:enc_time/1                                        281
>>>>>> 0.13     724  [      2.58]
>>>>>> prim_inet:ctl_cmd/3                                         287
>>>>>> 0.13     741  [      2.58]
>>>>>> hackney_http:parse_body/1                                   561
>>>>>> 0.13     761  [      1.36]
>>>>>> erlang:port_control/3                                       287
>>>>>> 0.14     785  [      2.74]
>>>>>> 'Elixir.Poison.Parser':array_values/3                       711
>>>>>> 0.14     791  [      1.11]
>>>>>> 'Elixir.Poison.Parser':number_frac/2                        788
>>>>>> 0.15     830  [      1.05]
>>>>>> 'Elixir.Poison.Parser':number_start/1                       788
>>>>>> 0.15     838  [      1.06]
>>>>>> erlang:binary_to_integer/1                                  788
>>>>>> 0.15     839  [      1.06]
>>>>>> 'Elixir.Poison.Parser':number_int/2                         784
>>>>>> 0.15     853  [      1.09]
>>>>>> hackney_response:stream_body/1                              281
>>>>>> 0.16     883  [      3.14]
>>>>>> 'Elixir.Poison.Parser':number_exp/3                         788
>>>>>> 0.16     903  [      1.15]
>>>>>> maps:from_list/1                                            729
>>>>>> 0.27    1514  [      2.08]
>>>>>> 'Elixir.Poison.Parser':number_complete/2                    788
>>>>>> 0.28    1571  [      1.99]
>>>>>> 'Elixir.Poison.Parser':number_digits/1                      784
>>>>>> 0.29    1620  [      2.07]
>>>>>> hackney_http:execute/2                                      567
>>>>>> 0.29    1641  [      2.89]
>>>>>> erts_internal:port_control/3                                287
>>>>>> 0.34    1905  [      6.64]
>>>>>> erlang:setelement/3                                        1728
>>>>>> 0.39    2228  [      1.29]
>>>>>> 'Elixir.Poison.Parser':object_pairs/3                      5077
>>>>>> 1.00    5634  [      1.11]
>>>>>> 'Elixir.Poison.Parser':number_digits_count/2               5947
>>>>>> 1.20    6765  [      1.14]
>>>>>> 'Elixir.Poison.Parser':object_name/2                       5077
>>>>>> 1.80   10167  [      2.00]
>>>>>> 'Elixir.Poison.Parser':value/2                             5769
>>>>>> 2.14   12061  [      2.09]
>>>>>> erlang:iolist_to_binary/1                                  9324
>>>>>> 2.23   12558  [      1.35]
>>>>>> erlang:binary_to_integer/2                                11587
>>>>>> 2.58   14537  [      1.25]
>>>>>> 'Elixir.Poison.Parser':string_escape/2                    19399
>>>>>> 4.10   23114  [      1.19]
>>>>>> 'Elixir.Poison.Parser':skip_whitespace/1                  21712
>>>>>> 7.95   44850  [      2.07]
>>>>>> 'Elixir.Poison.Parser':string_continue/2                  46845
>>>>>> 9.96   56241  [      1.20]
>>>>>> 'Elixir.Poison.Parser':string_chunk_size/2               303284
>>>>>>  60.04  338888  [      1.12]
>>>>>> -------------------------------------------------------  ------
>>>>>>  -------  ------  [----------]
>>>>>> Total:                                                   457768
>>>>>>  100.00%  564404  [      1.23]
>>>>>>
>>>>>> Indeed, parsing takes time (value indicated in µs) but this is about
>>>>>> half a second. When I run my 4 tests I could expect the test suite to 
>>>>>> take
>>>>>> 2 seconds if they run sequentially. Yet, the test suite takes more than 
>>>>>> 10
>>>>>> seconds to run.
>>>>>>
>>>>>>
>>>>>> > mix test --trace test/ex_tumblr/posts_test.exs
>>>>>>
>>>>>> ExTumblr.PostTest
>>>>>>   * test parse/1 can transform a generic map into a Post struct
>>>>>> (6.5ms)
>>>>>>
>>>>>> ExTumblr.PostsTest
>>>>>>   * test emits request to the right path (195.3ms)
>>>>>>   * test parses the http response into a Posts struct (55.6ms)
>>>>>>   * test specifies the api key in the query (33.7ms)
>>>>>>   * test sends a GET request (28.5ms)
>>>>>>
>>>>>>
>>>>>> Finished in 10.1 seconds
>>>>>> 5 tests, 0 failures
>>>>>>
>>>>>>
>>>>>> What I notice every time the suite runs is a ~10 seconds pause
>>>>>> between the two test cases. To be more specific:
>>>>>>
>>>>>> > mix test --trace test/ex_tumblr/posts_test.exs
>>>>>>
>>>>>> ExTumblr.PostTest
>>>>>>   * test parse/1 can transform a generic map into a Post struct
>>>>>> (6.5ms)
>>>>>> *############### 10 SECONDS PAUSE HERE ##############*
>>>>>> ExTumblr.PostsTest
>>>>>>   * test emits request to the right path (195.3ms)
>>>>>>   * test parses the http response into a Posts struct (55.6ms)
>>>>>>   * test specifies the api key in the query (33.7ms)
>>>>>>   * test sends a GET request (28.5ms)
>>>>>>
>>>>>>
>>>>>> Finished in 10.1 seconds
>>>>>> 5 tests, 0 failures
>>>>>>
>>>>>> If I comment all these tests but one, I observe the same behaviour
>>>>>> with a ~2 seconds pause. Every test basically adds its own ~2s pause.
>>>>>>
>>>>>> I already posted this in the slack chat where @micmus and @ericmj
>>>>>> were really kind and helpful but we couldn't find the cause.
>>>>>>
>>>>>> Can anybody find the problem ?
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>> --
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>>>>
>>>
>>>
>>> --
>>>
>>>
>>> *José Valim*
>>> www.plataformatec.com.br
>>> Skype: jv.ptec
>>> Founder and Director of R&D
>>>
>>>

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