fullstackpython.github.com/caching.html at gh-pages · simonlee2/fullstackpython.github.com · GitHub

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<!DOCTYPE html>

<title>Caching - Full Stack Python</title>

<!--[if lt IE 9]>

<![endif]-->

var _gaq = _gaq || [];

_gaq.push(['_setAccount', 'UA-19910497-7']);

_gaq.push(['_trackPageview']);

(function() {

var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;

ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';

var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);

})();

</script> </head>

<body>

</a>

<span class="logo-title"><a href="/">Full Stack Python</a></span>

</div>

</div> <div class="row">

<h1>Caching</h1>

<p>Caching can reduce the load on servers by storing the results of common

operations and serving the precomputed answers to clients. </p>

<p>For example, instead of retrieving data from database tables that rarely

change, you can store the values in-memory. Retrieving values from an

in-memory location is far faster than retrieving them from a database (which

stores them on a persistent disk like a hard drive.) When the cached values

change the system can invalidate the cache and re-retrieve the updated values

for future requests.</p>

<p>A cache can be created for multiple layers of the stack. </p>

<h2>Caching backends</h2>

<ul>

<li>

<p><a href="http://memcached.org/">memcached</a> is a common in-memory caching system.</p>

</li>

<li>

<p><a href="http://redis.io/">Redis</a> is a key-value in-memory data store that can

easily be configured for caching with libraries such as

<a href="https://github.com/sebleier/django-redis-cache">django-redis-cache</a>.</p>

</li>

</ul>

<h2>Caching resources</h2>

<ul>

<li>

<p>"<a href="https://bjornjohansen.no/caching-varnish-or-nginx">Caching: Varnish or Nginx?</a>"

reviews some considerations such as SSL and SPDY support when choosing

reverse proxy Nginx or Varnish.</p>

</li>

<li>

<p><a href="http://bizcoder.com/caching-is-hard-draw-me-a-picture">Caching is Hard, Draw me a Picture</a>

has diagrams of how web request caching layers work. The post is relevant

reading even though the author is describing his Microsoft code as the

impetus for writing the content.</p>

</li>

</ul>

<h2>Caching learning checklist</h2>

Analyze your web application for the slowest parts. It's likely there are

complex database queries that can be precomputed and stored in an in-memory

data store.</p>

Leverage your existing in-memory data store already used for session data

to cache the results of those complex database queries.

A <a href="/task-queues.html">task queue</a> can often be used to precompute the results

on a regular basis and save them in the data store.</p>

Incorporate a cache invalidation scheme so the precomputed results remain

accurate when served up to the user.</p>

<h3>What do you want to learn now that your app is responding faster?</h3>

How do I run Python outside the HTTP request-response cycle?

</p>

</div>

</a>

What can I learn about my users through web analytics?

</p>

</div>

What should I know about security to protect my app?

</p>

</div>

How do I automate the server configuration that I set up?

</p>

</div>

</div> <style type="text/css">

#mc_embed_signup{background:#fff; clear:left; font:12px "Helvetica Neue",Arial,sans-serif; }

/* Add your own MailChimp form style overrides in your site stylesheet or in this style block.

We recommend moving this block and the preceding CSS link to the HEAD of your HTML file. */

</style>

<hr/>

<h4>Interested in a complete Full Stack Python book with detailed tutorials and example code? Sign up here and you'll get an alert email if a book is created. No other emails will be sent other than sign up confirmation.</h4>

<label for="mce-EMAIL">Email Address</label>

</div>

</div>

</div>

</div>

</form>

</div>

var fnames = new Array();var ftypes = new Array();fnames[0]='EMAIL';ftypes[0]='email';fnames[1]='FNAME';ftypes[1]='text';fnames[2]='LNAME';ftypes[2]='text';

try {

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jqueryLoaded=true;

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var jqueryLoaded=false;

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var head= document.getElementsByTagName('head')[0];

if (!jqueryLoaded) {

var script = document.createElement('script');

script.type = 'text/javascript';

script.src = '//ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js';

head.appendChild(script);

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head.appendChild(style);

setTimeout('mce_preload_check();', 250);

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return;

}

var script = document.createElement('script');

script.type = 'text/javascript';

script.src = 'http://downloads.mailchimp.com/js/jquery.form-n-validate.js';

head.appendChild(script);

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var validatorLoaded=jQuery("#fake-form").validate({});

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setTimeout('mce_preload_check();', 250);

return;

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mce_init_form();

}

function mce_init_form(){

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var mce_validator = $("#mc-embedded-subscribe-form").validate(options);

$("#mc-embedded-subscribe-form").unbind('submit');//remove the validator so we can get into beforeSubmit on the ajaxform, which then calls the validator

options = { url: 'http://mattmakai.us2.list-manage.com/subscribe/post-json?u=b7e774f0c4f05dcebbfee183d&id=b22335388d&c=?', type: 'GET', dataType: 'json', contentType: "application/json; charset=utf-8",

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this.value = 'filled';

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return mce_validator.form();

success: mce_success_cb

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$('#mc-embedded-subscribe-form').ajaxForm(options);

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$('#mc-embedded-subscribe-form').each(function(){

this.reset();

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} else {

err_id = 'mce_tmp_error_msg';

html = '<div id="'+err_id+'" style="'+err_style+'"> '+msg+'</div>';

var input_id = '#mc_embed_signup';

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f = $(input_id).parent().parent().get(0);

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input_id = '#mce-'+fnames[index]+'-month';

f = $(input_id).parent().parent().get(0);

} else {

input_id = '#mce-'+fnames[index];

f = $().parent(input_id).get(0);

}

if (f){

$(f).append(html);

$(input_id).focus();

} else {

$('#mce-'+resp.result+'-response').show();

$('#mce-'+resp.result+'-response').html(msg);

}

} catch(e){

$('#mce-'+resp.result+'-response').show();

$('#mce-'+resp.result+'-response').html(msg);

}

</script>

</div>

<div class="panel-heading"><h3 class="panel-head">Caching</h3></div>

<a href="/">Full Stack Python</a> is an open book that explains

each Python web application stack layer and provides the

best web resources for those topics.

<hr/>

Need more detailed tutorials and walkthroughs than what is

presented here?

<a href="/email.html">Sign up for an email alert when that content is created.</a>

<hr/>

<a href="http://twitter.com/mattmakai">Matt Makai</a> built

this site with assistance from community pull requests. On GitHub

you can <a href="https://github.com/makaimc">follow Matt</a>

to see the daily changes.

</div>

<h3 class="panel-head">Table of Contents</h3>

</div>

<a href="/introduction.html" class="list-group-item smaller-item ">Introduction</a>

<a href="/web-frameworks.html" class="list-group-item smaller-item ">Web Frameworks</a>

<a href="/django.html" class="list-group-item smaller-item ">Django</a>

<a href="/flask.html" class="list-group-item smaller-item ">Flask</a>

<a href="/bottle.html" class="list-group-item smaller-item ">Bottle</a>

<a href="/other-web-frameworks.html" class="list-group-item smaller-item ">Other Web Frameworks</a>

<a href="/deployment.html" class="list-group-item smaller-item ">Deployment</a>

<a href="/servers.html" class="list-group-item smaller-item ">Servers</a>

<a href="/operating-systems.html" class="list-group-item smaller-item ">Operating Systems</a>

<a href="/web-servers.html" class="list-group-item smaller-item ">Web Servers</a>

<a href="/platform-as-a-service.html" class="list-group-item smaller-item ">Platform-as-a-service</a>

<a href="/wsgi-servers.html" class="list-group-item smaller-item ">WSGI Servers</a>

<a href="/source-control.html" class="list-group-item smaller-item ">Source Control</a>

<a href="/application-dependencies.html" class="list-group-item smaller-item ">Application Dependencies</a>

<a href="/configuration-management.html" class="list-group-item smaller-item ">Configuration Management</a>

<a href="/databases.html" class="list-group-item smaller-item ">Databases</a>

<a href="/no-sql-datastore.html" class="list-group-item smaller-item ">NoSQL Data Stores</a>

<a href="/cascading-style-sheets.html" class="list-group-item smaller-item ">Cascading Style Sheets</a>

<a href="/javascript.html" class="list-group-item smaller-item ">JavaScript</a>

<a href="/application-programming-interfaces.html" class="list-group-item smaller-item ">Application Programming Interfaces</a>

<a href="/api-integration.html" class="list-group-item smaller-item ">API Integration</a>

<a href="/api-creation.html" class="list-group-item smaller-item ">API Creation</a>

<a href="/static-content.html" class="list-group-item smaller-item ">Static Content</a>

<a href="/caching.html" class="list-group-item smaller-item active">Caching</a>

<a href="/task-queues.html" class="list-group-item smaller-item ">Task Queues</a>

<a href="/logging.html" class="list-group-item smaller-item ">Logging</a>

<a href="/monitoring.html" class="list-group-item smaller-item ">Monitoring</a>

<a href="/web-analytics.html" class="list-group-item smaller-item ">Web Analytics</a>

<a href="/web-application-security.html" class="list-group-item smaller-item ">Web Application Security</a>

<a href="/best-python-resources.html" class="list-group-item smaller-item ">Best Python Resources</a>

<a href="/about-author.html" class="list-group-item smaller-item ">About the Author</a>

<a href="/change-log.html" class="list-group-item smaller-item ">Change Log</a>

<a href="/future-directions.html" class="list-group-item smaller-item ">Future Directions</a>

</div>

</div></div>

<hr/>

<a href="http://www.mattmakai.com/" class="underline">Matt Makai</a>

2014

</div>

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fullstackpython.github.com/caching.html at gh-pages · simonlee2/fullstackpython.github.com · GitHub

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