%D field in Apache access logs - first or last byte?

apache logging access-log
skaffman picture skaffman · Jan 19, 2011 · Viewed 13.4k times · Source

The Apache Httpd manual has a section on custom access log formats. One of these options is the %D field, which is documented as

The time taken to serve the request, in microseconds.

Can anyone tell me what exactly this is measuring? Is it time-to-first-byte, or time-to-last-byte, for example, or something more complex than that?

I need this is demonstrate compliance to performance requirements, and I want to know exactly what's being measured here.

Answer

noodl picture noodl · Jan 19, 2011

It's the last byte or rather, apr_time_now() - request_rec->request_time which is worked out during the logging phase. That phase happens last in the processing cycle, after the response has been sent.

Related questions

how to make log4j to write to the console as well

Is there any way to tell to log4j to write its log to the file and to the console? thanks there are my properties: log4j.rootLogger=DEBUG,console,R log4j.rootLogger=INFO, FILE log4j.appender.CONSOLE=…

Read More
Best way to log POST data in Apache?

Imagine you have a site API that accepts data in the form of GET requests with parameters, or as POST requests (say, with standard url-encoded, &-separated POST data). If you want to log and analyze API calls, the GET …

Read More
Best way to rotate Apache log files

I've got an Apache server that has one access log file that is topping 600MB. This makes it really hard to search the file or parse it. What software or modules for Apache are available that will make a daily …

Read More