Slow performance

rubyonrails-talk
#1

Hello all, I found a strange dilemma here:

I have a table of several thousand rows and I experimented with these
two method to display them:

In this first method, I just put the follow in the view, let's call
the view, display.rhtml
<% for x in Cookbook.find(:all) %>
<%= x.recipe %>
<% end %>
The page displays all 5000 recipes in less than 2 seconds. I am quite
happy with it.

The second method, I put the find() business in the controller within
a render :update do |page|.

def showrecipe
   render :update do |page|
     page.replace_html 'displaydiv', :partial => 'recipe', :collection
=> find(:all, conditions => ["cuisine = ?", "italian"])
end
end

This method, when called, takes forever.

----> Can anyone be kind enough to hint why this is the case? <--

Thank You!

#2

Hmm... no index on the `cuisine` column? (I'm assuming that you really have :conditions as the : seems to be misssing.)

Also, do you really want to push that much data back with rjs? If all you need is to update a div, use the :update option on your link_to_remote.

You also don't say where the "forever" is taking place, for example, what does the log file contain? (I don't actually believe you since I'm never personally waited that long :wink:

-Rob

Rob Biedenharn http://agileconsultingllc.com
Rob@AgileConsultingLLC.com

#3

Hello Rob, Thank You Thank you Thank you for replying!!

Sorry about my confusing writing. Here's the improvement:

So I have the FAST version like this:
<html><body>
<% for i in Recipes.find(:all) %>
  <%= i.ingredients %>
<% end %>
</body</html>

All ingredients from the 5,000+ recipes show up in less than 1.5
seconds.

Then I have this slow version like this:
<html><body>
<%= link_to_remote "show ingredients", :update => "targetdiv", :url =>
{:action => "showIngredients"} %>
<div id="targetdiv">
</div>
</body></html>

and in the controller:
def showingredients
  render :update do |page|
    page.replace_html 'targetdiv', :partial => 'i', :collection =>
Recipes.find(:all)
  end
end

And in the partial 'i':
<%= i.ingredients %>

So that's all. The slow version takes as much as 14 seconds sometimes.

Any ideas?

#4

Hello Rob, Thank You Thank you Thank you for replying!!

Sorry about my confusing writing. Here's the improvement:

So I have the FAST version like this:
<html><body>
<% for i in Recipes.find(:all) %>
  <%= i.ingredients %>
<% end %>
</body</html>

All ingredients from the 5,000+ recipes show up in less than 1.5
seconds.

Then I have this slow version like this:
<html><body>
<%= link_to_remote "show ingredients", :update => "targetdiv", :url =>
{:action => "showIngredients"} %>
<div id="targetdiv">
</div>
</body></html>

and in the controller:
def showingredients
  render :update do |page|
    page.replace_html 'targetdiv', :partial => 'i', :collection =>
Recipes.find(:all)
  end
end

And in the partial 'i':
<%= i.ingredients %>

So that's all. The slow version takes as much as 14 seconds sometimes.

Any ideas?

Have you looked at this with Firefox and Firebug? You should be able to see how long the request takes. Then I'd see what changing to:

def showingredients
   render :update do |page|
     page.replace_html 'targetdiv', :partial => 'i', :collection => Recipes.find(:all, :limit => 10)
   end
end

does to the timing.

Actually, do you even get the right result after you wait for it? You have :update => "targetdiv", but then you're sending the javascript to do the replace. If you want to keep the :update, change the controller to be just:

def showingredients
   render :partial => 'i', :collection => Recipes.find(:all, :limit => 10)
end

Hope that helps.

-Rob

#5

Hey,

So, are you saying that when you render the 5000 recipes using an
ordinary browser request it's fast, but when you try to use AJAX to
update the page with 5000 recipes it's much slower?

Doesn't that seem sensible? The AJAX response for stuff like
page.replace_html will be escaped so that it can be evaluated by
javascript (so it will be a larger over-the-wire transfer) *and* the
javascript engine will have to process the response...

Sounds to me like the solution is staring you in the face - don't use
AJAX in the situations where it's faster to just render the whole page.

HTH
Trevor

#6

Hey Rob, thanks again for the swift reply.

I did mean to take out the :update part. Sorry about the confusion
(again).

I tried the :limit => 10, but it doesn't seem to help;(

I am doomed.

Nik

#7

Hey Trevor!, Thank You for commenting!

I totally agree with you. Okay, here's what I REALLY want to do, I
have for instance, Chinese food, Italian food, and etc, right, these
are menus on the left hand panel if you can imagine, and on the right-
hand side is this targetdiv that will contain all the recipes when the
"XYZ food" button is clicked. So I do want to make the targetdiv a
rather dynamic thing, you know what I mean? I tried this RJS business.
It failed (to achieve the speed) and I beat my brains out to try to
speed it up.

I guess I should just load all on the page and hide them until
toggled?

Nik

#8

May I add just one more thing I saw in the command prompt when loading
the page using the fast and slow method:

For the FAST method: it show only a few new lines
For the slow method: it shows a few thousand lines of these:
Rendered /recipe/_i <0.00100>
...

Does that help?

#9

Just for curiosity, what the hell will you do with 5000 recipes in ONE
page ??

Use the limit option set to 20 at most, then use pagination and stuff to
get more recipes...

Lemme see the page with 5000 recipes, just wonder about the usability

Regards

matthi

Nik schrieb:

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