I need some time data for optimizing nginx. But I can not find the meaning of $connection_time
variable.
Offical document explains(http://nginx.org/en/docs/http/ngx_http_core_module.html#var_connection_time):
connection_time
connection time in seconds with a milliseconds resolution (1.19.10)
In the access log, I only know $connection_time
is always greater than $request_time
.
CodePudding user response:
$connection_time
is alive time of TCP connection used by a http request.
HTTP keep-alive and HTTP/2 allows a single TCP connection to send and receive multiple HTTP requests/responses. so the $connection_time
should be always greater than $request_time
;
We can prove it using the following nginx configure file
http {
...
log_format testlog '[$time_local] "$request" connection_time= $connection_time request_time= $request_time';
}
server {
listen 80;
server_name localhost;
root /www;
location / {
index index.html index.htm;
}
access_log /var/log/nginx/test.access.log testlog;
error_log /var/log/nginx/test.error.log;
# disable cache
expires -1;
add_header Last-Modified $date_gmt;
add_header Cache-Control 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0';
if_modified_since off;
etag off;
# disable keep alive
location /keep-alive-off/ {
keepalive_timeout 0;
}
# enable keep alive
location /keep-alive-on/ {
keepalive_timeout 300s;
}
}
access.log
[12/Oct/2021:06:38:03 0000] "GET /keep-alive-off/test.pdf HTTP/1.1" connection_time= 0.212 request_time= 0.210
[12/Oct/2021:06:38:05 0000] "GET /keep-alive-off/test.pdf HTTP/1.1" connection_time= 0.252 request_time= 0.253
[12/Oct/2021:06:38:06 0000] "GET /keep-alive-off/test.pdf HTTP/1.1" connection_time= 0.200 request_time= 0.203
[12/Oct/2021:06:38:11 0000] "GET /keep-alive-on/test.pdf HTTP/1.1" connection_time= 0.240 request_time= 0.239
[12/Oct/2021:06:38:14 0000] "GET /keep-alive-on/test.pdf HTTP/1.1" connection_time= 3.268 request_time= 0.185
[12/Oct/2021:06:38:17 0000] "GET /keep-alive-on/test.pdf HTTP/1.1" connection_time= 6.177 request_time= 0.168
We can see that if turn off HTTP keep-alive
to disallow TCP connection reuse, $request_time
would always be equal with $connection_time