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Editorial Team
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Asked: 2026-06-01T11:19:56+00:00

I’m trying to cache Python/flask responses with memcached. I then want to serve the

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I’m trying to cache Python/flask responses with memcached. I then want to serve the cache using nginx. I’m using flask code that looks something like this:

from flask import Flask, render_template
from werkzeug.contrib.cache import MemcachedCache

app = Flask(__name__)

cache = MemcachedCache(['127.0.0.1:11211'])

@app.route('/')
def index():
    index = cache.get('request:/')
    if index == None:
        index = render_template('index.html')
        cache.set('request:/', index, timeout=5 * 60)
    return index

if __name__ == "__main__":
    app.run()

and an nginx site configuration that looks something like this:

server {
    listen 80;

    location / {
        set $memcached_key "request:$request_uri";
        memcached_pass 127.0.0.1:11211;

        error_page 404 405 502 = @cache_miss;
    }

    location @cache_miss {
        uwsgi_pass   unix:///tmp/uwsgi.sock;
        include      uwsgi_params;

        error_page  404  /404.html;
    }
}

However, when it pulls from the cache the html code is prefixed with a V, contains \u000a characters (line feeds) and garbled local characters, and is suffixed with “p1 .” as such:

V<!doctype html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">\u000a<head>\u000a  <meta http-equiv="content-type" content="text/html; charset=UTF-8" />\u000a  <meta http-equiv="content-language" content="no">\u000a\u000a  <title>

[...]

\u000a\u000a</body>\u000a</html>
p1
.

Despite Content-Type being “text/html; charset=utf-8”. Supposedly the V […] p1 . thing might have something do with chunked transfer encoding something, a flag that is not present in the response header. What should I do?

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1 Answer

  1. Editorial Team

    Yay, I fixed it! The nginx configuration was correct before I changed chunked, the python/flask code however should have been:

    @app.route('/')
def index():
    rv = cache.get('request:/')
    if rv == None:
        rv = render_template('index.html')
        cachable = make_response(rv).data
        cache.set('request:/', cachable, timeout=5 * 60)
    return rv

    That is, I should only cache the data, and that can only be done, afaik, if I do make_response first

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