mysql - Django querysets in a distributed application -


i have 4 ec2 servers running django 1.3.2 application uwsgi. share mysql server on amazon rds. i'm experiencing behavior if new objects created through admin , try:

get_object_or_404(class, pk=new_object.pk)

sometimes find object, other times return 404.

what going on?

this how i'm using get_object_or_404:

# module level variables if settings.debug:     articles = news.objects.filter(status='live') else:     articles = news.objects.all()   dev view(request, slug):     article = get_object_or_404(articles, slug=slug)     ....

if restart uwsgi processes, problem goes away.

questions , things i've tried:

  1. are module level variables problem? i've tried debug since querysets lazy doesn't seem problem.
  2. is cache issue? i've restarted memcache , cleared nginx's cache issue remains.
  3. is rds issue? haven't found answer this.
  4. is queryset cache issue? haven't found answer this, , don't know how.

everything works expected on single server, have multiple servers, start experience behavior.

module level variables problem - querysets "lazy" long not used (iteration, evalution, whatever), start retrieving records populate cache (hint: django open-source, can readthecode(tm) when doc not enough).

you might have troubles transaction isolation level if use innodb tables (cf django's doc on last point).


Comments

Post a Comment

Popular posts from this blog

node.js - Bad Request - node js ajax post -

i'm using express 3.0 , node v0.11.0. have button submits form , i'm using ajax post data json object node server. client code is: $('#contact').submit(function(e) { console.log('submit called'); var formdata = json.stringify($('form').serializeobject()); console.log(formdata); $.ajax({ url: "http://localhost:3000/savedata/", type: "post", datatype: 'json', data: {objectdata: formdata}, contenttype: "application/json", complete: function() { console.log('process complete'); }, success: function(data) { console.log('process sucess'); }, error: function() { console.log('process error'); }, }); return false; }); then on server: var express = require('express'); var app = express(); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyparser());...
Read more

Why does Ruby on Rails generate add a blank line to the end of a file? -

running rails generate controller foo home results in: class foocontroller < application controller def home end end (there's nothing on line in actual file, blank line) is there purpose blank line? it's common use newline indicate end of line, last line. many editors (like vi, use) add in newline silently. consensus text files (especially in unix world) should end in newline, , there have been problems historically if wasn't present. why should text files end newline? the tool used count lines in file "wc" counts newlines in file, without trailing newline show 3 instead of 4. it improves readability of templates used in generator. consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb to remove trailing newline, template have last line of: end<% end -%> instead of: end <% end -%> that seems less readable me. the discussion below refers ...
Read more

uitableview - Create and use custom prototype table cells in xamarin ios using storyboard -

Image
is possible create , use 'custom' prototype table cells in xamarin ios (monotouch) using storyboard? i find stuart lodge explaining method using xib/nibs: http://www.youtube.com/watch?feature=player_embedded&v=vd1p2gz8jfy let's answer question! looking one. :) 1) open storyboard have viewcontroller tableview: add prototype cell (if there no cell added before): customize cell want (in case there custom uiimage , label): remember set height of cell. select whole tableview , properties window select "layout" tab. on top of properties window should see "row height" - put appropriate value: now select prototype cell once again. in properties window type name of class (it create code-behind class it). in case "friendscustomtableviewcell". after provide "identifier" cell. can see "friendcell". last thing set "style" property set custom. "name" field should empty. once click ...
Read more