Mercurial > hg > nginx-site

annotate xml/en/docs/njs/preload_objects.xml @ 3009:2e8c1384d211

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Documented ngx.shared.SharedDict.items in njs Reference.
author Yaroslav Zhuravlev <yar@nginx.com>
date Tue, 12 Sep 2023 21:32:51 +0100
parents 48f245493600
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
2984
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
1 <?xml version="1.0"?>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
2
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
3 <!--
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
4 Copyright (C) Nginx, Inc.
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
5 -->
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
6
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
7 <!DOCTYPE article SYSTEM "../../../../dtd/article.dtd">
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
8
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
9 <article name="Understanding preloaded objects"
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
10 link="/en/docs/njs/preload_objects.html"
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
11 lang="en"
3002
48f245493600 Slightly updated text in Preload Objects in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents: 2984
diff changeset
12 rev="2"
2984
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
13 toc="no">
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
14
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
15 <section id="summary">
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
16
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
17 <para>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
18 For each incoming request njs creates a separate virtual machine.
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
19 This brings a lot of benefits such as predictable memory consumption
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
20 or requests isolation.
3002
48f245493600 Slightly updated text in Preload Objects in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents: 2984
diff changeset
21 However, as all requests are isolated,
2984
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
22 if a request handler needs to access some data,
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
23 it has to read it by itself.
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
24 This is not efficient especially when the amount of data is large.
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
25 </para>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
26
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
27 <para>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
28 To address this limitation,
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
29 a preloaded shared object was introduced.
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
30 Such objects are created immutable and do not have prototype chains:
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
31 their values cannot be changed, properties cannot be added or removed.
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
32 </para>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
33
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
34 </section>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
35
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
36
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
37 <section id="working_with_preload_objects"
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
38 name="Working with preload objects">
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
39
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
40 <para>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
41 Here are some examples of how to work with a preload object in njs:
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
42
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
43 <list type="bullet">
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
44
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
45 <listitem>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
46 access properties by name:
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
47 <programlisting>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
48 preloaded_object.prop_name
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
49 preloaded_object[prop_name]
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
50 </programlisting>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
51 </listitem>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
52
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
53 <listitem>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
54 enumerate properties:
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
55 <programlisting>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
56 for (i in preloaded_object_name) {
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
57 ...
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
58 }
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
59 </programlisting>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
60 </listitem>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
61
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
62 <listitem>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
63 apply non-modifying built-in methods using <literal>call()</literal>:
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
64 <programlisting>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
65 Array.prototype.filter.call(preloaded_object_name, ...)
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
66 </programlisting>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
67 </listitem>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
68
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
69 </list>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
70 </para>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
71
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
72 </section>
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
73
cc475ba7d406 Added Preload Objects article in njs.
Yaroslav Zhuravlev <yar@nginx.com>
parents:
diff changeset
74 </article>