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Path: utzoo!utgpu!water!watmath!clyde!mtunx!mtune!petsd!pedsga!chip
From: chip@pedsga.UUCP
Newsgroups: comp.unix.questions,comp.unix.wizards,comp.unix.microport
Subject: Re: Trouble killing processes in SysV/AT
Message-ID: <575@pedsga.UUCP>
Date: 5 May 88 16:32:20 GMT
References: <3950@killer.UUCP> <3951@killer.UUCP> <3967@killer.UUCP>
Reply-To: chip@pedsga.UUCP (Chip Maurer,7361)
Organization: Concurrent Computer Corp., Tinton Falls, N.J.
Lines: 28

In article <3967@killer.UUCP> richardh@killer.UUCP writes:
>In article <3951@killer.UUCP>, wnp@killer.UUCP (Wolf Paul) writes:
>> Can anyone enlighten me as to what causes a process to become "immortal"
>> in System VR2,  or Microport UNIX System V/AT, to be more specific?
>> I have encountered this a number of times, where it would be impossible
>> even for root to kill a process; 
>While I've never seen this under Microport SYS V/AT, I have seen it under
>Intel Xenix 3.4 (SYS III based). Like you, I was amazed when the command
>kill -9 pid
>executed by root didn't remove the process entry from the ps display. However

I have seen this too, on Xelos, Concurrent's port of SVR2.  It seems
that when a process is flow controlled off, no amount of killing by
root would remove the process.  I originally had this problem trying
to get an imagen running over NTS, a LAN in our building.  NTS
has the ability to ignore (pass through) or handle flow control (^S, ^Q).  
I originally had the NTS process flow control (other options were wrong
as well).  When the imagen driver filled the NTS buffer, it would flow 
control the driver.  For reasons unknonst to me, it would never flow
control the driver back on.  I was stuck with a process I couldn't kill.
I don't know the kernel software that well, but I guess that even though
signals were arriving for the process, the kernel would not reschedule it.

-- 
         Chip ("My grandmother called me Charles once. ONCE!!") Maurer
     Concurrent Computer Corporation, Tinton Falls, NJ 07724 (201)758-7361
        uucp: {mtune|purdue|rutgers|princeton|encore}!petsd!pedsga!chip
                       arpa: pedsga!chip@UXC.CSO.UIUC.EDU