Purpose of Apache process in ubuntu precise64 Apache 2.2.22

Question

Using worker MPM, StartServers 3 and ThreadsPerChild 25, we see following.

vagrant@precise64:$ sudo apachectl -v
Server version: Apache/2.2.22 (Ubuntu)
Server built:   Feb 13 2012 01:51:56

vagrant@precise64:$ ps -aef | grep apache2
root      6147     1  0 01:41 ?        00:00:00 /usr/sbin/apache2 -k start
www-data  6148  6147  0 01:41 ?        00:00:00 /usr/sbin/apache2 -k start
www-data  6149  6147  0 01:41 ?        00:00:00 /usr/sbin/apache2 -k start
www-data  6150  6147  0 01:41 ?        00:00:00 /usr/sbin/apache2 -k start
www-data  6151  6147  0 01:41 ?        00:00:00 /usr/sbin/apache2 -k start

vagrant@precise64:$ ps -aefL | grep apache2 | grep -v grep | awk '{print $2;}' | sort -
n | uniq -c
      1 6147
      1 6148
     27 6149
     27 6150
     27 6151

It is clear that pid 6147 is main process, 6149, 6150, 6151 are child processes. Can someone explain purpose of pid 6148? It does not listen on any port.

Thanks, Sameer

Answer 1

Maybe it's this: Citing https://httpd.apache.org/docs/2.4/mod/worker.html:

In addition to the set of active child processes, there may be additional child processes which are terminating, but where at least one server thread is still handling an existing client connection. Up to MaxRequestWorkers terminating processes may be present, though the actual number can be expected to be much smaller.