View source for Short Notes on Python

== Timing, and memory, on Linux ==

=== Timing ===

On Linux, it's safer to use <tt>time.time()</tt>
<pre>import time
t = time.time()
# do some stuff
print "stuff took %1.3f", time.time() - t, "seconds"</pre>
On Windows, AFAIK, it's safer to use <tt>time.clock()</tt>

=== Memory ===

For me, the following does a good job getting memory usage (in kB) on Linux:
<pre>import resource
print resource.getrusage(resource.RUSAGE_SELF).ru_maxrss</pre>
Since <tt>resource</tt> is standard package, it should work on Windows too, but I don't know if it does, or what units are used if it works.

== Importing Files ==

If you need to import a file '../mylib/commons.py', you can use the following snippet:
 <nowiki>import sys, os
fld = os.path.realpath(os.path.abspath(os.path.join('..', 'mylib')))
if fld not in sys.path:
    sys.path.insert(0, fld)
import commons

# use your commons.py module now...
commons.super_function()</nowiki>

== uWSGI, nginx, Flask ==

* install uwsgi (incl. uwsgi python plugin), python flask, and nginx,

=== Setting Up uWSGI ===

* create ''main.py'' file that will hold the server logic, for instance:
<pre>from flask import Flask

app = Flask(__name__)


@app.route("/")
def hello():
    return "hello there!"</pre>
* create uwsgi config file, ''wsgi.ini'' ('''minimal''' version here; read uwsgi docs for head-spinning array of configurables):
<pre>[uwsgi]
module          = wsgi:app
master          = true
processes       = 5
socket          = 127.0.0.1:8000
protocol        = http
plugin          = python</pre>
* run uwsgi
 uwsgi --ini wsgi.ini
* check that all works on http://localhost:8000/

=== Adding nginx Layer ===

* remove the "protocol" directive from ''wsgi.ini'', and add "die-on-term":
<pre>[uwsgi]
module          = wsgi:app
master          = true
processes       = 5
socket          = 127.0.0.1:8000
plugin          = python
die-on-term     = true</pre>
* add a new vhost to nginx - ''/etc/nginx/sites-available/app.nginx'':
<pre>server {
    listen 80;
    server_name my.awesome.domain;
    location / {
        include uwsgi_params;
        uwsgi_pass 127.0.0.1:8000;
    }
}</pre>
** communication through socket is also possible (see ''socket'', ''chmod-socket'', ''vacuum'' and other directives for uWSGI)
** of course, create link in ''/etc/nginx/sites-enabled/'', and restart nginx,
* create ''systemd'' file for uWSGI, ''/etc/systemd/system/uwsgi-app.service'':
<pre>[Unit]
Description=Job that runs the uWSGI app

[Service]
Type=simple
WorkingDirectory=/home/project/flask-test/
ExecStart=/usr/bin/uwsgi --ini wsgi.ini</pre>

Then you can start and stop the uwsgi service using:
 # systemctl start uwsgi-app.service
 # systemctl stop uwsgi-app.service