Graphical console in stable/10 stuck on heavy writing

Mark Martinec Mark.Martinec+freebsd at
Mon Dec 23 00:47:08 UTC 2013

FreeBSD amd64, recent stable/10:

When running some task on a graphical console window
and that task writes lots of output to a console, the
console gets stuck after some time (like 20 minutes),
output stops, keyboard appears unresponsive, alt-ctrl-Fn
is unable to switch consoles - but the machine seems
otherwise sane: I can log in over ssh, file system and
processes are healthy, CPU not busy.

This was first noticed trying to rebuild kde from
ports in a console window. Same happened when bulk
updating packages from a remote site and the pkg update
was busily writing its output to a console.

The same heavy tasks (e.g. ports rebuild) can run
just fine in an ssh session, or in a konsole / xterm.

As a final proof, I tried a perl one-liner which
writes a line (a count and some text) ten times per
second: it manages to screw up the console window
in about 6 minutes.

Interestingly, while the console output is stuck
and I blindly type a command on a keyboard (no echo),
then run a shutdown from another (ssh) session,
the console output gets unstuck during shutdown,
rapidly displays the missing lines, including the
echo of a command typed blindly previously, along
with its output.

Btw, this never happened on this machine while it was
running 9.2 or older versions.

Anybody seen this or can reproduce it?


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