*BSD News Article 16861


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From: adam@veda.is (Adam David)
Newsgroups: comp.os.386bsd.questions
Subject: Strange problem with pseudo-tty
Message-ID: <C87Jwq.2qG@veda.is>
Date: 6 Jun 93 16:16:59 GMT
Organization: Veda Systems, Iceland
Lines: 23

Has anyone seen this, or know why it happens?

When a user hangs up abnormally from a session, active programs remain
attached to their ptys and the next person to get that pty (next person
to login or open a window) whether that person is the same one or someone
else, ends up attached to both the hung process and the new session at
the same time. This happens with any number of programs, but it might
only affect sessions which use iScreen (I have only seen it there, but
this is not necessarily the cause).

Any such hung program uses lots of CPU. It is random whether the input
and output streams are talking to the old process or the new process,
so some pretty strange effects occur.

The only way I have found to recover is for the previous user (or the
superuser) to kill -9 the old process. I am rather inclined to think it
is a problem with iScreen because it has also happened often that screen -r
cannot find the previous session after logging back in.

This is 386bsd 0.1.2.3 with syscons2.

--
adam@veda.is