I've noticed these in httpd access log starting with Apache2.2:
::1 - - [09/May/2008:14:53:29 -0400] "GET / HTTP/1.0" 200 5043 "-" "Apache (internal dummy connection)"The apache server occasionally hits localhost to signal its children. See the apache wiki for more info.
"When Apache HTTP Server manages its child processes, it needs a way to wake up processes that are listening for new connections. To do this, it sends a simple HTTP request back to itself...
These requests are perfectly normal and you do not, in general, need to worry about them. They can simply be ignored."
Unfortunately, the homepage I host is a dynamic one and this becomes very costly during busy times. I see a large number of those internal dummy connection requests during an apache graceful restart (SIGUSR1) and at the same time the cpu load on the Apache2.2 server maxes out at nearly 100%. I do not see this cpu load during a graceful restart on apache 2.0 httpd servers.
With the below mod_rewrite rule in place I was able to reduce the load by pointing http request coming from HTTP_USER_AGENT, "internal dummy request" to an empty static html page.
RewriteEngine on
RewriteCond %{HTTP_USER_AGENT} ^.*internal\ dummy\ connection.*$ [NC]
RewriteRule ^/$ /blank.html [L]Also, removed logging of such requests via:
SetEnvIf Remote_Addr "::1" dontlog
CustomLog /var/log/httpd/access.log combined env=!dontlog