lmc@denelcor.UUCP (Lyle McElhaney) (11/15/84)
Several time now we have attempted to use shutdown to bring our 750 running 4.2 dow. This normally works as expected, but sometimes the shutdown just seems to disappear. The task line is still in the ps -aux: root 16954 0.0 0.4 53 21 co I < 0:00 shutdown +5 but we never hear from it again. When we bring the system down with /etc/halt, it finds that "some processes won't die". There is one zombie in the ps listing... Why does shutdown not? -- Lyle McElhaney (hao,brl-bmd,nbires,csu-cs,scgvaxd)!denelcor!lmc
jim@haring.UUCP (11/16/84)
Shutdown attempts to write to everyone's terminal. Now, someone can block that message (with a ^S or whatever) and the write hangs. Shutdown has an alarm() round the write, to arrange to catch such action. However, the alarm handling routine 'does nothing', it is only to interrupt the write system call, but, since on 4.2, the write system call is restartable, you go back to where you were... You need to have a setjmp/longjmp construct instead. Later versions of 4.2 have this fixed. Jim McKie Centrum voor Wiskunde en Informatica, Amsterdam mcvax!jim
chuqui@nsc.UUCP (Cheshire Chuqui) (11/19/84)
In article <592@denelcor.UUCP> lmc@denelcor.UUCP (Lyle McElhaney) writes: >Several time now we have attempted to use shutdown to bring our 750 running >4.2 dow. This normally works as expected, but sometimes the shutdown just >seems to disappear. > >but we never hear from it again. When we bring the system down with >/etc/halt, it finds that "some processes won't die". There is one >zombie in the ps listing... I've seen this on a 4.2 780 as well. It seems to be caused by shutdown attempting to output to a tty port that is hung, wedging the process on an I/O wait. I haven't figured out why this happens-- it could be that someone has left a terminal in a ^S state and the buffer fills up on shutdown and it waits forever for the terminal. perhaps a timeout in the wall code will help, I haven't bothered to try to fix it. chuq -- From the Department of Bistromatics: Chuq Von Rospach {cbosgd,decwrl,fortune,hplabs,ihnp4,seismo}!nsc!chuqui nsc!chuqui@decwrl.ARPA This plane is equipped with 4 emergency exits, at the front and back of the plane and two above the wings. Please note that the plane will be travelling at an average altitude of 31,000 feet, so any use of these exits in an emergency situation will most likely be futile.