django is very slow

Question

Some profiling shows template rendering as the culprit. (I'm trying on a page with ONLY cached queries.) But still, the template is very simple. the most complex part is a nested loop that runs for 10 times, but if everything goes well the nested loop doesn't run because it's cached. (like in my testing)

that is

{% for p in posts %}
 --{{p.by.username}}
 --{{p.text}}
 {% cache 600 p p.timestamp %}
    {% for img in p.images.all %}
      --{{img.path}}
    {% endfor %}
 {% endcache %}
{% endfor %}

I get ~80 req/s on the dev. server for this page. (I found I can multiply that number by 3 in the production deploy) For a comparison, I get 1000req/s for a trivial template that only contains a short static string.

Is that a known issue? How do I go about correcting/avoiding it?

Answer 1

In development mode, django does a lot of things to ease developing(for example: code reloading; template rendering for every request if template used; ...).

In production mode, deploy a WSGI server before django is preferred. Such wsgi might be gunicorn, uWSGI, ...

A typical production web server's layout might be: nginx -> gunicorn -> django

A simple comparison(django official tutorial code with a very simple "Hello World! @ time" template):

{% block content %}
    <p> Hello World! @ {{ now }}</p>
{% endblock %}

Development mode

run with django directly

python manage.py runserver

run apache-ab to test

ab -n1000 -c10 http://127.0.0.1:8000/polls/helloworld

Server Software:        WSGIServer/0.2 # django
Server Hostname:        127.0.0.1
Server Port:            8000

Document Path:          /polls/helloworld
Document Length:        59 bytes

Concurrency Level:      10
Time taken for tests:   3.438 seconds
Complete requests:      1000
Failed requests:        0
Total transferred:      242000 bytes
HTML transferred:       59000 bytes
Requests per second:    290.87 [#/sec] (mean)
Time per request:       34.380 [ms] (mean)
Time per request:       3.438 [ms] (mean, across all concurrent requests)
Transfer rate:          68.74 [Kbytes/sec] received

Production mode

run with gunicorn

../bin/gunicorn -w4 mysite.wsgi # with 4 workers

run apache-ab to test

ab -n1000 -c10 http://127.0.0.1:8000/polls/helloworld

Server Software:        gunicorn/19.7.1  # gunicorn
Server Hostname:        127.0.0.1
Server Port:            8000

Document Path:          /polls/helloworld
Document Length:        59 bytes

Concurrency Level:      10
Time taken for tests:   0.618 seconds
Complete requests:      1000
Failed requests:        0
Total transferred:      248000 bytes
HTML transferred:       59000 bytes
Requests per second:    1619.10 [#/sec] (mean)
Time per request:       6.176 [ms] (mean)
Time per request:       0.618 [ms] (mean, across all concurrent requests)
Transfer rate:          392.13 [Kbytes/sec] received