Running out of Unix98 PTYs in 2.2.13pre14

Jarno Paananen (jpaana@s2.org)
14 Oct 1999 00:08:19 +0300


Hi,

the problem is that the Unix98 PTY numbers don't seem to get
reused. With a maximum of 256 configured in the kernel it
takes 1-2 weeks to run out of PTYs.

At the moment the situation is like this (the machine had to be
booted yesterday because of this and now it seems we have to do
it again before end of the week):

crw------- 1 chery tty 136, 0 Oct 13 21:34 0
crw--w---- 1 pekangas tty 136, 1 Oct 13 23:59 1
crw------- 1 jpaana tty 136, 104 Oct 14 00:00 104
crwx------ 1 jpaana tty 136, 108 Oct 14 00:00 108
crw------- 1 jpaana tty 136, 3 Oct 13 23:59 3
crw------- 1 jpaana tty 136, 4 Oct 14 00:00 4
crw------- 1 chery tty 136, 43 Oct 13 23:59 43
crw------- 1 chery tty 136, 44 Oct 13 21:34 44
crw------- 1 jpaana tty 136, 5 Oct 13 23:59 5
crw------- 1 jpaana tty 136, 6 Oct 14 00:00 6
crw------- 1 jpaana tty 136, 75 Oct 14 00:00 75
crw------- 1 jpaana tty 136, 95 Oct 13 23:53 95

And this is all in /dev/pts. Lsof doesn't reveal any extra open
PTYs. After number 255 is opened all programs complain about not
getting a PTY.

The kernel version is 2.2.13pre14 compiled with gcc 2.7.2.3. The
same symptom appeared in 2.2.12, but possibly not in 2.2.10 (at
least that kernel got an uptime of 62 days).

Could this be a userland problem with something taking up PTYs,
a glibc bug (using 2.1.2 from Debian Potato), or a genuine
kernel problem?

Any help is very welcome...

// Jarno

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