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comparison xml/en/docs/http/ngx_http_upstream_module.xml @ 316:1fb1c077658b

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Documented the following directives: "keepalive", "proxy_http_version", and "fastcgi_keep_conn".
author Ruslan Ermilov <ru@nginx.com>
date Fri, 13 Jan 2012 18:10:34 +0000
parents 34246e706f48
children 4f907cde0382
comparison
equal deleted inserted replaced
315:e00f8f8c0486 316:1fb1c077658b
77 server backend2.example.com; 77 server backend2.example.com;
78 server backend3.example.com <emphasis>down</emphasis>; 78 server backend3.example.com <emphasis>down</emphasis>;
79 server backend4.example.com; 79 server backend4.example.com;
80 } 80 }
81 </example> 81 </example>
82 </para>
83
84 </directive>
85
86
87 <directive name="keepalive">
88 <syntax><value>connections</value></syntax>
89 <default/>
90 <context>upstream</context>
91 <appeared-in>1.1.4</appeared-in>
92
93 <para>
94 Activates cache of connections to upstream servers.
95 </para>
96
97 <para>
98 The <value>connections</value> parameter sets the maximum number of
99 keepalive connections to upstream servers that are retained in
100 the cache per one worker process.
101 If there are more idle connections to retain to an upstream than
102 are specified by this number, the least recently used ones will
103 be closed.
104 <note>
105 It should be noted that <literal>keepalive</literal> directive
106 does not limit the total number of connections that nginx worker
107 process can open to upstream servers.
108 The new connections are always created on demand.
109 The <value>connections</value> parameter should be set low enough
110 to allow upstream servers to process additional new incoming
111 connections as well.
112 </note>
113 </para>
114
115 <para>
116 Example configuration of memcached upstream with keepalive connections:
117 <example>
118 upstream memcached_backend {
119 server 127.0.0.1:11211;
120 server 10.0.0.2:11211;
121
122 keepalive 32;
123 }
124
125 server {
126 ...
127
128 location /memcached/ {
129 set $memcached_key $uri;
130 memcached_pass memcached_backend;
131 }
132
133 }
134 </example>
135 </para>
136
137 <para>
138 For HTTP, the <link doc="ngx_http_proxy_module.xml" id="proxy_http_version"/>
139 directive should be set to “<literal>1.1</literal>”
140 and the <header>Connection</header> header field should be cleared:
141 <example>
142 upstream http_backend {
143 server 127.0.0.1:8080;
144
145 keepalive 16;
146 }
147
148 server {
149 ...
150
151 location /http/ {
152 proxy_pass http://http_backend;
153 proxy_http_version 1.1;
154 proxy_set_header Connection "";
155 ...
156 }
157 }
158 </example>
159 </para>
160
161 <para>
162 <note>
163 Alternatively, HTTP/1.0 persistent connections can be used by passing the
164 <header>Connection: Keep-Alive</header> header field to an upstream server,
165 though this is not recommended.
166 </note>
167 </para>
168
169 <para>
170 For FastCGI servers, it is required to set
171 <link doc="ngx_http_fastcgi_module.xml" id="fastcgi_keep_conn"/>
172 for keepalive connections to work:
173 <example>
174 upstream fastcgi_backend {
175 server 127.0.0.1:9000;
176
177 keepalive 8;
178 }
179
180 server {
181 ...
182
183 location /fastcgi/ {
184 fastcgi_pass fastcgi_backend;
185 fastcgi_keep_conn on;
186 ...
187 }
188 }
189 </example>
190 </para>
191
192 <para>
193 <note>
194 When using load balancer modules other than the default
195 round-robin, it is necessary to activate them before
196 the <literal>keepalive</literal> directive.
197 </note>
198
199 <note>
200 SCGI and uwsgi protocols do not define keepalive connections.
201 </note>
82 </para> 202 </para>
83 203
84 </directive> 204 </directive>
85 205
86 206