I restarted apache and it is up now. I don't know what happened. But
last log was:
[Tue Mar 27 18:00:00 2012] [notice] Graceful restart requested, doing restart
panic: pthread_key_create failed
Is there any document that discusses the setup? Also I am not longer
sure what configuration is used to regenerate the wiki (so I can add
another user to maintain locked pages).