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

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) 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:

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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)  wrote:

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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:

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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  wrote:

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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)    wrote:

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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

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