Date: Sat, 3 Oct 1998 12:19:28 -0400 (EDT) From: Brian Tao <taob@risc.org> To: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> Cc: FREEBSD-CURRENT <freebsd-current@FreeBSD.ORG> Subject: Re: Processes stuck waiting for tty drain? Message-ID: <Pine.GSO.3.96.981003121349.23916I-100000@tor-dev1.nbc.netcom.ca> In-Reply-To: <199810021456.KAA24945@khavrinen.lcs.mit.edu>
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On Fri, 2 Oct 1998, Garrett Wollman wrote:
>
> Since it was running on a pty, probably something had gone wrong
> with the process on the master side, and so the buffer wasn't
> getting drained.
Hrm, so this is a telnetd-related problem then? It happened again
during a cvsup -L 2 of the ports collection (again, lots of output to
the tty). An echo or cat to the device would block, although the
output queue would not rise above 1301 bytes for that tty:
# pstat -t | fgrep -C ttyp | head
64 pty lines
LINE RAW CAN OUT IHIWT ILOWT OHWT LWT COL STATE SESS PGID DISC
ttyp0 0 0 0 512 448 1296 256 0 OCc 0 0 term
ttyp1 0 2 1301 512 448 1296 256 0 OCcA f1885a00 12689 term
ttyp2 0 0 0 512 448 1296 256 0 OCc f12588c0 12715 term
3 0 0 0 0 0 0 0 0 - 0 0 term
4 0 0 0 0 0 0 0 0 - 0 0 term
# ps -laxt p1
UID PID PPID CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND
1000 5008 5007 0 18 0 452 324 pause Is p1 0:00.03 -csh (csh)
0 5010 5008 0 18 0 1396 1112 pause I p1 0:01.29 -usr/local/bin/tcsh
0 12689 5010 0 2 0 5264 4828 select S+ p1 0:31.41 cvsup -g -L2 -Pm /usr/local/etc/cvsupfile
# kill 12689
# ps -laxt p1
UID PID PPID CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND
1000 5008 5007 0 18 0 452 324 pause Is p1 0:00.03 -csh (csh)
0 5010 5008 0 18 0 1396 1112 pause I p1 0:01.29 -usr/local/bin/tcsh
0 12689 5010 0 4 0 5264 4828 ttywri S+ p1 0:31.41 cvsup -g -L2 -Pm /usr/local/etc/cvsupfile
# kill -1 12689
# ps -laxt p1
UID PID PPID CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND
1000 5008 5007 0 18 0 452 324 pause Is p1 0:00.03 -csh (csh)
0 5010 5008 0 4 0 1396 1112 ttywri S+ p1 0:01.29 -usr/local/bin/tcsh
# ps -lfp 5007
UID PID PPID CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND
0 5007 148 0 2 0 880 548 select Is ?? 0:06.62 telnetd
# kill 5007
# ps -laxt p1
UID PID PPID CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND
So far, the problem has not reappeared if I ssh in instead of
telnetting in.
--
Brian Tao (BT300, taob@risc.org)
"Though this be madness, yet there is method in't"
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