Comment 4 for bug 1028470

I could verify getting the same log messages on my system.

This however seems to be not directly related to the problem. I see the same messages, when testing it on Ubuntu 11.10. But the apache remains stable and repsonsive on this older version of ubuntu.

I have found some interesting behavior, when using the -k switch with ab to ensure there are really only the specified amount of processes used and no process is busy waiting for the connection to close:
$ ab -k -n 5000 -c 999 http://localhost/
.... all requests will complete without error
$ curl http://localhost/
<html><body><h1>It works!</h1>
<p>This is the default web page for this server.</p>
<p>The web server software is running but no content has been added, yet.</p>
</body></html>
$ curl http://localhost/
... no answer

so here you can literally see how the connection #1001 (the "magic number", that appeared before) is breaking apache. i think maybe its some kind of buffer running full?