anatomy of a large django site

Anatomy of a large Django site

Andy McKay Mozilla

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Vancouver

PythonZope and Plone...now at Mozilla

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Using Djangohttp://www.djangoproject.com

Credit: http://www.flickr.com/photos/abiavati/3110357974/

1. About the site2. Performance3. Localisation4. Reuse

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1. About the site

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All code is open:https://github.com/jbalogh/zamboni

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All* bugs are open:https://bugzilla.mozilla.org

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Convert from CakePHP (remora)

to Django (zamboni)

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mozillaCredit: http://www.flickr.com/photos/improbcat/4177702580/

Changing one URL at a time from CakePHP to Django

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General trend to move away from PHP and do more Python and Django

How large?250k+ addons

150 mn views month500 mn API hits day

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Lines of code

PHPPython

40k18k

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Lines of code

PHPPython

Unit tests

40k18k15k

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No pages go out until they are faster

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running both php and python side by side. a few issues on that

3 zeus load balancers24 django (and php) 1 mysql + 4 slaves3 memcached3 sphinx1 rabbitmq + 2 celeryd1 redis master + 1 slave

Credit: http://www.flickr.com/photos/tbridge/15300843/ mozilla

2. Performance

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As usual, database bottleneck

Cache machinehttp://bit.ly/cache-machine

mozillaCredit: http://www.flickr.com/photos/mwichary/4063534688/

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from django.db import modelsimport caching.base

class Addon(caching.base.CachingMixin, models.Model): ... status = models.IntegerField() objects = caching.base.CachingManager()

available as a mixin

need to addin the custom manager

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>>> Addon.objects.filter(status=public)>>> len(connection.queries) 13

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>>> Addon.objects.filter(status=public)>>> len(connection.queries) 13

>>> Addon.objects.filter(status=public)>>> len(connection.queries) 13

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Invalidation

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md5(‘select... a’) [addon 3615]

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md5(‘select... a’) [addon 3615]

addon 3615 md5(‘select... a’)

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md5(‘select... a’) [addon 3615]

md5(‘select... b’) [addon 3615, addon 1685]

addon 3615 md5(‘select... a’)md5(‘select... b’)

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Memcachedrules = cache.get(3615)rules.add('select...')cache.set(3615, rules)

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Redisredis.SADD(3615, ‘select...’)

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Home page20+ addons

400+ sql queries

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standard answer in django is select-related

add-on version

files

version

version

files

files

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django: select_related()http://bit.ly/select-related

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Transformerhttp://bit.ly/queryset-transform

simonw

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@staticmethod def transformer(addons): addon_dict = dict((a.id, a) for a in addons) vs = filter(None, (a.current_version_id for a in addons) versions = list(Version.objects.filter(id__in=vs)) for version in versions: addon_dict[version.addon_id].current_version = version

slightly outdated example

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Home page20+ addons

~14 sql queries

big SQL statements... :(

14313 character

UpdateCalled on startup

about:config ☞ extensions.update.url

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IncomingUncached

8,000 req/sec1,600 req/sec

Im used to Plone in the bad old days

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IncomingUncached

PHP

8,000 req/sec1,600 req/sec550 req/sec

Im used to Plone in the bad old days

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PHP Python

v1Plain

Django

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PHP Python

v2Min. SQL

queries

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oh god

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PHP Python

v3Django and

raw SQLmax-requests 200, actually we hit 210

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PHP Python

v4WSGI

no Django

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PHP Python

v5Pooling,

optimised queries

Thats 700 req/secwhich translates into

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Reducing the SQL queries...doesn’t always help

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mySQL query cache is fast

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Celeryhttp://celeryproject.org

mozillaCredit: http://www.flickr.com/photos/chiotsrun/3843988392/

Push things asyncemail

image processingadd-on validation

specifically fixing data changes between php and python

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from celeryutils import task

@taskdef update_tag(tag, **kw): tag.update_stat()

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from celeryutils import task

@task(rate_limit='60/h')def update_tag(tag, **kw): tag.update_stat()

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from tasks import update_tag

update_tag.delay(tag)

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Measurement

Timing Middlewarehttp://bit.ly/timing-ware

mozillaCredit: http://www.flickr.com/photos/wwarby/3297205226/

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3. Localization

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40+ languagesincluding rtl

show site in arabic?

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Database strings

content translated

and

templates

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class Addon(caching.base.CachingMixin, models.Model): ... name = models.ForeignKey(Translation)

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addon.name = 'name'addon.save()

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addon.name = 'name'addon.save()

addon.name = {'fr': 'la nomme'}addon.save()

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Templates

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Django{% blocktrans with app=request.APP %}

Add-ons for {{ app }} {% endblocktrans %}

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Jinja2http://jinja.pocoo.org/

{{ _('Add-ons for {0}')|f(request.APP) }}

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Python Unicode hellUnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 16: ordinal

not in range(128)

4. Reuse

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Bleachhttp://pypi.python.org/pypi/

mozillaCredit: http://www.flickr.com/photos/maisonbisson/3350954463/

>>> bleach.clean('an <script>evil()</script> example')

'an &lt;script&gt;evil()&lt;/script&gt; example'

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>>> bleach.linkify('an http://ex.com url')

'an <a href="http://ex.com" rel="nofollow">http://ex.com</a> url'

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Javascript tests

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django-qunithttp://bit.ly/django-qunit

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kumar

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test('English', function() {    z.refreshL10n('en-us');    equals($('textarea:visible', this.sandbox).text().trim(),           'Firebug integrates with Firefox to put ' + 'a wealth of development tools...');});

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test('Japanese', function() {    z.refreshL10n('ja');    equals($('textarea:visible', this.sandbox).text().trim(),           'Firebug は、Web ページを閲覧中にクリック一つ ' +

' で使える豊富な開発ツールを Firefox' +           ' に統合します。あなたはあらゆる');});

Use HudsonJenkinshttp://bit.ly/jstestnet

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So we use hudson for CI, but haven’t got the automated tests in yet

Hoping to do this via jstestnet

Flake8http://bit.ly/flake8

mozillaCredit: http://www.flickr.com/photos/nebarnix/357779131/

pep 8py flakesMacCabe

~/sandboxes/zamboni(632719) $ flake8 apps/editors/tasks.pyapps/editors/tasks.py:1: 'datetime' imported but unusedapps/editors/tasks.py:3: 'stat' imported but unused

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Playdohhttp://bit.ly/mozilla-playdoh

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fred wenzel

Credit: http://www.flickr.com/photos/ahmee/97960570/

Basis for new projects

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Celery supportJinja2 supportSimple migrations

By default: SHA-512 password hashing X-Frame-Options: DENY secure and httponly flags on cookies

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fred wenzel

Take inspiration from...but not the best for you

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for example jinja2 which makes integration with lots of django addons possible, but a bit harder

Questions?@andymckay

andym@mozilla.comandym on irc.freenode.net, irc.mozilla.org

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