forked from mattmakai/fullstackpython.com
-
Notifications
You must be signed in to change notification settings - Fork 0
/
caching.html
426 lines (419 loc) · 22.2 KB
/
caching.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
<!DOCTYPE html>
<html lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="author" content="Matt Makai">
<meta name="description" content="Full Stack Python explains each layer of the web application stack, from the server up through the rendering in a user's browser.">
<link rel="shortcut icon" href="theme/img/fsp-fav.png">
<title>Caching - Full Stack Python</title>
<link href="theme/css/fsp.css" rel="stylesheet">
<!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.3.0/respond.min.js"></script>
<![endif]-->
<link href="//netdna.bootstrapcdn.com/font-awesome/4.1.0/css/font-awesome.css" rel="stylesheet">
<script type="text/javascript">
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 href="https://github.com/makaimc/fullstackpython.github.com" class="github">
<img style="position: absolute; top: 0; right: 0; border: 0;" src="http://s3.amazonaws.com/github/ribbons/forkme_right_darkblue_121621.png" alt="Fork me on GitHub" />
</a>
<div class="container">
<div class="row">
<div class="col-md-12">
<div class="logo-header-section">
<a href="/" style="text-decoration: none; border: none;"><img src="theme/img/fsp-logo.png" height="52" width="52" class="logo-image" style="padding-top: 1px;"/></a>
<span class="logo-title"><a href="/">Full Stack Python</a></span>
</div>
</div>
</div> <div class="row">
<div class="col-md-8">
<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>
<p><i class="fa fa-check-square-o"></i>
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>
<p><i class="fa fa-check-square-o"></i>
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>
<p><i class="fa fa-check-square-o"></i>
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>
<div class="row">
<div class="col-md-3">
<div class="well select-next">
<a href="/task-queues.html" class="btn btn-success btn-full"><i class="fa fa-tasks fa-2x"></i></a>
<p class="under-btn">
How do I run Python outside the HTTP request-response cycle?
</p>
</div>
</div>
<div class="col-md-3">
<div class="well select-next">
<a href="/web-analytics.html" class="btn btn-success btn-full"><i class="fa fa-dashboard fa-2x"></i></a>
</a>
<p class="under-btn">
What can I learn about my users through web analytics?
</p>
</div>
</div>
<div class="col-md-3">
<div class="well select-next">
<a href="/web-application-security.html" class="btn btn-success btn-full"><i class="fa fa-lock fa-inverse fa-2x"></i></a>
<p class="under-btn">
What should I know about security to protect my app?
</p>
</div>
</div>
<div class="col-md-3">
<div class="well select-next">
<a href="/configuration-management.html" class="btn btn-success btn-full"><i class="fa fa-gears fa-inverse fa-2x"></i></a>
<p class="under-btn">
How do I automate the server configuration that I set up?
</p>
</div>
</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/>
<div id="mc_embed_signup">
<form action="http://mattmakai.us2.list-manage.com/subscribe/post?u=b7e774f0c4f05dcebbfee183d&id=b22335388d" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank" novalidate>
<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>
<div class="row">
<div class="col-md-9">
<label for="mce-EMAIL">Email Address</label>
<input type="email" value="" name="EMAIL" class="required email form-control" id="mce-EMAIL">
</div>
<div class="col-md-3">
<input type="submit" value="Subscribe" name="subscribe" id="mc-embedded-subscribe" class="btn btn-success" style="margin-top: 20px;">
</div>
<div id="mce-responses" class="clear">
<div class="response" id="mce-error-response" style="display:none"></div>
<div class="response" id="mce-success-response" style="display:none"></div>
</div> <!-- real people should not fill this in and expect good things - do not remove this or risk form bot signups-->
<div style="position: absolute; left: -5000px;"><input type="text" name="b_b7e774f0c4f05dcebbfee183d_b22335388d" value=""></div>
</div>
</form>
</div>
<script type="text/javascript">
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 {
var jqueryLoaded=jQuery;
jqueryLoaded=true;
} catch(err) {
var jqueryLoaded=false;
}
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);
if (script.readyState && script.onload!==null){
script.onreadystatechange= function () {
if (this.readyState == 'complete') mce_preload_check();
}
}
}
var err_style = '';
try{
err_style = mc_custom_error_style;
} catch(e){
err_style = '#mc_embed_signup input.mce_inline_error{border-color:#6B0505;} #mc_embed_signup div.mce_inline_error{margin: 0 0 1em 0; padding: 5px 10px; background-color:#6B0505; font-weight: bold; z-index: 1; color:#fff;}';
}
var head= document.getElementsByTagName('head')[0];
var style= document.createElement('style');
style.type= 'text/css';
if (style.styleSheet) {
style.styleSheet.cssText = err_style;
} else {
style.appendChild(document.createTextNode(err_style));
}
head.appendChild(style);
setTimeout('mce_preload_check();', 250);
var mce_preload_checks = 0;
function mce_preload_check(){
if (mce_preload_checks>40) return;
mce_preload_checks++;
try {
var jqueryLoaded=jQuery;
} catch(err) {
setTimeout('mce_preload_check();', 250);
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);
try {
var validatorLoaded=jQuery("#fake-form").validate({});
} catch(err) {
setTimeout('mce_preload_check();', 250);
return;
}
mce_init_form();
}
function mce_init_form(){
jQuery(document).ready( function($) {
var options = { errorClass: 'mce_inline_error', errorElement: 'div', onkeyup: function(){}, onfocusout:function(){}, onblur:function(){} };
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",
beforeSubmit: function(){
$('#mce_tmp_error_msg').remove();
$('.datefield','#mc_embed_signup').each(
function(){
var txt = 'filled';
var fields = new Array();
var i = 0;
$(':text', this).each(
function(){
fields[i] = this;
i++;
});
$(':hidden', this).each(
function(){
var bday = false;
if (fields.length == 2){
bday = true;
fields[2] = {'value':1970};//trick birthdays into having years
}
if ( fields[0].value=='MM' && fields[1].value=='DD' && (fields[2].value=='YYYY' || (bday && fields[2].value==1970) ) ){
this.value = '';
} else if ( fields[0].value=='' && fields[1].value=='' && (fields[2].value=='' || (bday && fields[2].value==1970) ) ){
this.value = '';
} else {
if (/\[day\]/.test(fields[0].name)){
this.value = fields[1].value+'/'+fields[0].value+'/'+fields[2].value;
} else {
this.value = fields[0].value+'/'+fields[1].value+'/'+fields[2].value;
}
}
});
});
$('.phonefield-us','#mc_embed_signup').each(
function(){
var fields = new Array();
var i = 0;
$(':text', this).each(
function(){
fields[i] = this;
i++;
});
$(':hidden', this).each(
function(){
if ( fields[0].value.length != 3 || fields[1].value.length!=3 || fields[2].value.length!=4 ){
this.value = '';
} else {
this.value = 'filled';
}
});
});
return mce_validator.form();
},
success: mce_success_cb
};
$('#mc-embedded-subscribe-form').ajaxForm(options);
});
}
function mce_success_cb(resp){
$('#mce-success-response').hide();
$('#mce-error-response').hide();
if (resp.result=="success"){
$('#mce-'+resp.result+'-response').show();
$('#mce-'+resp.result+'-response').html(resp.msg);
$('#mc-embedded-subscribe-form').each(function(){
this.reset();
});
} else {
var index = -1;
var msg;
try {
var parts = resp.msg.split(' - ',2);
if (parts[1]==undefined){
msg = resp.msg;
} else {
i = parseInt(parts[0]);
if (i.toString() == parts[0]){
index = parts[0];
msg = parts[1];
} else {
index = -1;
msg = resp.msg;
}
}
} catch(e){
index = -1;
msg = resp.msg;
}
try{
if (index== -1){
$('#mce-'+resp.result+'-response').show();
$('#mce-'+resp.result+'-response').html(msg);
} else {
err_id = 'mce_tmp_error_msg';
html = '<div id="'+err_id+'" style="'+err_style+'"> '+msg+'</div>';
var input_id = '#mc_embed_signup';
var f = $(input_id);
if (ftypes[index]=='address'){
input_id = '#mce-'+fnames[index]+'-addr1';
f = $(input_id).parent().parent().get(0);
} else if (ftypes[index]=='date'){
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>
<!--End mc_embed_signup--> </div>
<div class="col-md-offset-1 col-md-3" id="sidebar">
<div class="panel panel-success">
<div class="panel-heading"><h3 class="panel-head">Caching</h3></div>
<div class="panel-body">
<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/>
There's a work-in-progress
<a href="/full-stack-python-map.pdf">subjects map (.pdf)</a>
that visually lays out each chapter in addition to the table of
contents found below.
<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>
</div>
<div class="panel panel-success">
<div class="panel-heading">
<h3 class="panel-head">Table of Contents</h3>
</div>
<div class="list-group">
<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="/morepath.html" class="list-group-item smaller-item ">Morepath</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="/platform-as-a-service.html" class="list-group-item smaller-item ">Platform-as-a-service</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="/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="/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="/web-design.html" class="list-group-item smaller-item ">Web Design</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="/continuous-integration.html" class="list-group-item smaller-item ">Continuous Integration</a>
<a href="/code-metrics.html" class="list-group-item smaller-item ">Code Metrics</a>
<a href="/configuration-management.html" class="list-group-item smaller-item ">Configuration Management</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="/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="/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="/development-environments.html" class="list-group-item smaller-item ">Development Environments</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>
<a href="/what-full-stack-means.html" class="list-group-item smaller-item ">What "Full Stack" Means</a>
<a href="/why-use-python.html" class="list-group-item smaller-item ">Why Use Python?</a>
<a href="/websockets.html" class="list-group-item smaller-item ">WebSockets</a>
<a href="/docker.html" class="list-group-item smaller-item ">Docker</a>
</div>
</div>
</div></div>
<hr/>
<div class="footer pull-right">
<a href="http://www.mattmakai.com/" class="underline">Matt Makai</a>
2014
</div>
</div>
<script type="text/javascript">
setTimeout(function(){var a=document.createElement("script");
var b=document.getElementsByTagName("script")[0];
a.src=document.location.protocol+"//dnn506yrbagrg.cloudfront.net/pages/scripts/0016/5846.js?"+Math.floor(new Date().getTime()/3600000);
a.async=true;a.type="text/javascript";b.parentNode.insertBefore(a,b)}, 1);
</script></body>
</html>