On Mon, 17 Feb 2014, Karl E. Jorgensen wrote:
So init knows that you want to shut down/reboot.. My guess is that one of the "early" init scripts are hanging.
Thank you for the hint. I followed your test method and the test result show this problem has nothing to do with a hanging service.
The first in asciibetic order is 'apache2'. If I stop it, it succumb easily without hanging. I described previously that after issuing reboot/halt/shutdown, the website being served by apache2 is still running, hence init daemon did not attempt to shutdown even the earliest service. It seems init knows I want to shutdown, and acknowledge it, and then ignored it.
In my past years I came across many services that refuses to die, and they were killed after timed out, so normally init daemon knows how to kill without grace.