Put this code somewhere in one of your INSTALLED_APPS `__init__.py` file. This code will replace the django.template.loader.get_template with cached version. Standard get_template function from django reads and parses the template code every time it's called. This version calls (if DEBUG set to False) it only once per template. After that it gets a Template object from template_cache dictionary. On django http server with template code like that:
{% extends "index.html" %}
{% block content %}
{% if form.has_errors %}
<p>Your username and password didn't match. Please try again.</p>
{% endif %}
<form method="post" action=".">
<table>
<tr><td><label for="id_username">Username:</label></td><td>{{ form.username }}</td></tr>
<tr><td><label for="id_password">Password:</label></td><td>{{ form.password }}</td></tr>
</table>
<input type="submit" value="login" />
<input type="hidden" name="next" value="{{ next }}" />
</form>
{% endblock %}
ab -n 100 on mac os x 10.5 core 2 duo 2 ghz with 2 GB of RAM gives
forge-macbook:~ forge$ ab -n 100 http://127.0.0.1:8000/login/
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/
Benchmarking 127.0.0.1 (be patient).....done
Server Software: WSGIServer/0.1
Server Hostname: 127.0.0.1
Server Port: 8000
Document Path: /login/
Document Length: 934 bytes
Concurrency Level: 1
Time taken for tests: 0.432934 seconds
Complete requests: 100
Failed requests: 0
Write errors: 0
Total transferred: 120200 bytes
HTML transferred: 93400 bytes
Requests per second: 230.98 [#/sec] (mean)
Time per request: 4.329 [ms] (mean)
Time per request: 4.329 [ms] (mean, across all concurrent requests)
Transfer rate: 270.25 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 0
Processing: 3 3 1.5 4 12
Waiting: 3 3 1.2 3 12
Total: 3 3 1.5 4 12
Percentage of the requests served within a certain time (ms)
50% 4
66% 4
75% 4
80% 4
90% 4
95% 5
98% 10
99% 12
100% 12 (longest request)
without template caching, and
forge-macbook:~ forge$ ab -n 100 http://127.0.0.1:8000/login/
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/
Benchmarking 127.0.0.1 (be patient).....done
Server Software: WSGIServer/0.1
Server Hostname: 127.0.0.1
Server Port: 8000
Document Path: /login/
Document Length: 934 bytes
Concurrency Level: 1
Time taken for tests: 0.369860 seconds
Complete requests: 100
Failed requests: 0
Write errors: 0
Total transferred: 120200 bytes
HTML transferred: 93400 bytes
Requests per second: 270.37 [#/sec] (mean)
Time per request: 3.699 [ms] (mean)
Time per request: 3.699 [ms] (mean, across all concurrent requests)
Transfer rate: 316.34 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 0
Processing: 3 3 0.9 3 9
Waiting: 2 3 0.9 3 8
Total: 3 3 0.9 3 9
Percentage of the requests served within a certain time (ms)
50% 3
66% 3
75% 3
80% 3
90% 3
95% 5
98% 8
99% 9
100% 9 (longest request)
with caching enabled.
In both cases DEBUG is set to False.
- template
- cache
- performance
- optimization
Watch out! Previous versions of this snippet (without the values list) were vulnerable to SQL injection attacks. The "correct" solution is probably to wait until [ticket 4102](http://code.djangoproject.com/ticket/4102) hits the trunk. But here's my temporary fix while we wait for that happy day.
Django's model.save() method is a PITA:
1. It does a SELECT first to see if the instance is already in the database.
2. It has additional database performance overhead because it writes all fields, not just the ones that have been changed.
3. It overwrites other model fields with data that may be out of date. This is a real problem in concurrent applications, like almost all web apps.
If you just want to update a field or two on a model instance which is already in the database, try this:
update_fields(user,
email='[email protected]',
is_staff=True,
last_login=datetime.now())
Or you can add it to your models (see below) and then do this:
user.update_fields(
email='[email protected]',
is_staff=True,
last_login=datetime.now())
To add it to your model, put it in a module called granular_update, then write this in your models.py:
import granular_update
class User(models.Model):
email = models.EmailField()
is_staff = models.BooleanField()
last_login = models.DateTimeField()
update_fields = granular_update.update_fields
- fields
- model
- save
- performance
- field
- update
- integrity
- consistency