[web-devel] Performance of Yesod 0.7 fourteen times slower than Rails 2.3?

Michael Snoyman michael at snoyman.com
Wed Mar 23 08:13:18 CET 2011

This was a great example of a performance bug being exactly where you
don't expect it. I'm planning on writing up a blog post on this
adventure later, but for the quick summary: the Criterion benchmarks
have gone from 23.7ms (== 23,700us) to 141us. Meaning this is a 200
fold speedup for some operations. This came from switching a large
monad transformer stack to a single RWS monad. But more on that in the
blog post.

I've run your test a few more times: it still seems like there's a
slowdown from the database code, but I think the widget performance
bug was the big issue. After some more testing on my end, I'll put the
code on Hackage. Would you give the test another shot after that?

Thanks again for bringing this up!


On Mon, Mar 21, 2011 at 5:41 PM, Sven Koschnicke (GFXpro)
<s.koschnicke at gfxpro.com> wrote:
> Hello,
> I think your guess wasn't completely wrong. I tested with Sqlite now, and
> with that rails and yesod are equally slow (rails 11.81 secs vs yesod 11.36
> secs). But its also interesting that your code change speeds it up.
> (I put the sqlite benchmark at
> https://github.com/SKoschnicke/performance-test/tree/sqlite)
> My first guess was actually that its the marshalling which slows yesod so
> much and that rails uses some clever optimizations there, but I haven't got
> enough insight to validate that.
> Greetings
>  Sven
> On 03/21/2011 01:49 PM, Michael Snoyman wrote:
>> Looks like my initial guess was completely wrong: on my system, almost
>> no time is spent on the database query. Instead, it looks like there's
>> some kind of performance issue with Hamlet. For example, changing line
>> 20 of Handler/Quote.hs from "addWidget" to "addHtml" increases
>> performance dramatically (25 sec to 4.5 sec). I'll need to spend some
>> more time to properly diagnose the problem. Again, thanks for bringing
>> this to my attention.
>> Michael
>> On Mon, Mar 21, 2011 at 12:40 PM, Michael Snoyman<michael at snoyman.com>
>>  wrote:
>>> Firstly, thank you for running this benchmark: it's the only way we
>>> can find out where Yesod needs to be fixed.
>>> I haven't had a chance to look into the code properly, but it looks
>>> like this is more a test of the database backend than of the web
>>> framework. I'll try to get to this myself later, but it would be very
>>> interesting to see the difference in response times between PostgreSQL
>>> and sqlite. Currently, persistent-sqlite binds directly to the sqlite
>>> C API, while persistent-postgresql uses HDBC. It's entirely possible
>>> that HDBC is adding some overhead.
>>> One of the items on our wish list[1] is to migrate away from HDBC.
>>> Having hard numbers like you are providing will help us figure out our
>>> priorities a bit better.
>>> Thanks,
>>> Michael
>>> [1] http://wiki.yesodweb.com/Wishlist
>>> On Mon, Mar 21, 2011 at 12:10 PM, Sven Koschnicke (GFXpro)
>>> <s.koschnicke at gfxpro.com>  wrote:
>>>> Hello,
>>>> I'm coming from a Rails background and was very impressed by the
>>>> features of
>>>> the Yesod Web Framework. Working on an trading app in Rails I wanted to
>>>> port
>>>> some features of this app to a Yesod app just to learn the framework and
>>>> because we have some performance issues with Rails.
>>>> The first thing I noticed was that the Yesod app was significantly
>>>> slower
>>>> than the Rails app at trivial tasks. I am very astonished about that. I
>>>> thought Rails should be slower because of its interpreted nature. I made
>>>> some benchmarking and measured that a simple Rails app is fourteen times
>>>> faster than a Yesod app that did the same thing (loading some records
>>>> from
>>>> the database and displaying them). Did I made a mistake or is my
>>>> understanding, that the compiled app should be faster, just wrong?
>>>> I documented the results on github:
>>>> https://github.com/SKoschnicke/performance-test
>>>> Greetings
>>>>  Sven Koschnicke
>>>> _______________________________________________
>>>> web-devel mailing list
>>>> web-devel at haskell.org
>>>> http://www.haskell.org/mailman/listinfo/web-devel

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