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

Michael Snoyman michael at snoyman.com
Sat Mar 26 21:57:20 CET 2011 

Let's say that we have a template [$hamlet|foo #{bar} baz|]. With
addHamlet, we essentially end up with the code:

addHamlet $ string "foo " `mappend` toHtml bar `mappend` string " baz"

With addWidget, we end up with:

addWidget $ do
    addHtml $ string "foo "
    addHtml $ toHtml bar
    addHtml $ string " baz"

As some of the recent benchmarking blog posts should point out,
operations in monad stacks (like addHamlet and addHtml) are more
expensive. Since addWidget incurs three of those instead of just one,
I'm not surprised it's slower. It would be nice to try and optimize
away some of that overhead, but I'm not sure if it's possible.

Overall, as funny as this sounds, I think allowing high-level Yesod
code to be about on a par with high-level Rails is a good place to be
right now. Yesod was written with the idea of *allowing* high
performance by making correct architectural choices, such as relying
on ByteString and Builder appropriately. However, it hasn't actually
undergone significant performance tuning. We're now far enough along
towards a stable API that we *have* started that optimization process:
starting at the bottom of the software stack, just look at the Warp
benchmark numbers. And even Yesod-the-framework beats out
non-framework Ruby code.

It seems that some of our higher level abstractions, like Persistent
and Widgets, could stand to be optimized. The next release of Yesod
will hopefully begin this process by replacing String with Text
throughout the codebase. But to continue this properly, I'd really
like help from the community. The more people who submit cases like
Sven's where Yesod is simply performing slower than expected, the
faster we'll track down inefficiencies.

But just to drive home the point more: Rails is a framework that (to
the best of my knowledge) has had many eyes staring at it and
optimizing it. Yesod is relatively young and has not undergone much
performance tuning. If we're already gaining a slight edge on Rails
now, just imagine what will happen when our focus shifts to
performance tuning between the 0.9 and 1.0 releases.

Michael

On Sat, Mar 26, 2011 at 8:38 PM, Greg Weber <greg at gregweber.info> wrote:
> using RAILS_ENV=production ./script/server
> ree 1.8.7 ruby-pg driver
> 21s
> ruby 1.9 pg driver
> 16-17s
> given there are a few time columns I tried "gem install home_run"
> and RAILS_ENV=production home_run ./script/server
> It didn't seem to make a difference- I think time object creation is lazy in
> Rails.
> Yesod with persistent-postgresql-0.4.0.1 gets 17s
> But then I looked at the code.
> For the template it is using: addWidget $(widgetFile "quote-index")
> I changed it too: addHamlet $(hamletFile "quote-index")
> and the time dropped down to 13-14s
> So finally, we are beating Rails- if we can't beat Rails on a benchmark that
> should be considered a horrible defect :)
> Here is a patch to fix widgetFile, although we should probably investigate
> why addWidget is slower.
> https://github.com/gregwebs/yesod/commit/32d11707f3d5bec73a5c3002f3924c58d82112a6
> On Fri, Mar 25, 2011 at 12:41 AM, Michael Snoyman <michael at snoyman.com>
> wrote:
>>
>> Hi Sven,
>>
>> Can I ask you to try things out one more time, this time with
>> persistent-postgresql 0.4.0.1? I think I fixed some more of the
>> issue[1].
>>
>> Thanks,
>> Michael
>>
>> [1] http://docs.yesodweb.com/blog/improving-persistent-performance
>>
>> On Wed, Mar 23, 2011 at 9:23 AM, Sven Koschnicke (GFXpro)
>> <s.koschnicke at gfxpro.com> wrote:
>> > Great that you found a way to speed things up! I'm looking forward to
>> > the
>> > blog post. I will run some more tests with the improved code, just let
>> > me
>> > know when its available. Is someone working on improving the postgres
>> > database backend? Maybe I could help there, the bad performance with
>> > postgres is really a showstopper for me.
>> >
>> > Sven
>> >
>> > On 03/23/2011 08:13 AM, Michael Snoyman wrote:
>> >>
>> >> 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!
>> >>
>> >> Michael
>> >>
>> >> 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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