debrunne%uirvld.csl.uiuc.edu@uxc.cso.uiuc.edu (Christian H. Debrunner) (02/14/89)
In v7n139 Danielle Heinzer <ESC1298@ESOC.BITNET> writes: >Since one week, I have observed the following: I cannot rlogin the Sun >3/260 file server in a shelltool from my Sun3/50. I see the motd and the >prompter of the remote file server, but I cannot enter anything.... I have also had problems with rlogins, cmdtools, and shelltools hanging, and I found that it only occurred when the pseudo-tty (pty) assigned to the rlogin, cmdtool or shelltool was open for input or output in some other (usually a background) process. I saw two different failure modes. The rlogin, cmdtool, or shelltool either crashed when the first character was typed (it seemed to interpret every character as a ^D), or it would seem to be in "raw" mode (no echo, no CR -> NL mapping). I sent a detailed report of how to recreate this bug to the SUN hotline, but they were unable to reproduce it. After I had sent them several test cases that demonstrated the bug on our system, none of which they could reproduce, they wrote to say they were "researching the problem". That was in November. I have found two solutions (workarounds) to this problem: 1) Stop (~ ^Z) the rlogin or close (but do not quit) the broken cmdtool or shelltool. This will tie up the broken pseudo-tty (pty), so the next rlogin, cmdtool, or shelltool will use a different pty. Repeat until you get a working one. Note that if you kill the rlogin, cmdtool, or shelltool and start a new one, you will most likely get the same pty again and it will still not work. 2) Find out which pty the rlogin, cmdtool or shelltool is using, and use that handiest of handy utilities "ofiles" (available in the archives) to find all processes which have that pty open. If the processes in question are expendable (or easily restarted), kill them. The problem can be avoided by running all background jobs with stdin, stdout and stderr redirected. Since our users have started running their background jobs with all IO redirected, we have not seen any more hung ptys. I realize that there are any number of other possible causes for the symptoms described in the original note, but when I read that a shelltool once hadn't worked on the server, it occurred to me that they might be experiencing the hanging pty problem. Chris Debrunner debrunne@uicsl.csl.uiuc.edu (217) 333-1368
siedelbe@stout.ucar.edu (Mike Siedelberg) (02/23/89)
I also have had this happen to a few of my sun 4s running 4.0 and other sysmgrs at NCAR have mentioned it too. It has always happened when a user has left background processes running after logout. The process seems like it doesn't want to release the ttypx and as you say, the workaround is to leave the rlogin process going and then rlogin on another pseudo tty. Also Sun says they cannot dupicate it. Maybe we should gang up on Sun :-). I think I will at least call them back and say that I am not the only one out here experiencing this prob. mike siedelberg Research Applications Program Field Systems Group National Center for Atmospheric Research Boulder, Co 80303 (303)497-2013 mike@toadwar.ucar.edu
pl@uunet.uu.net (Pertti Lehtinen) (03/08/89)
by siedelbe@stout.ucar.edu (Mike Siedelberg): > I also have had this happen to a few of my sun 4s running 4.0 and other > sysmgrs at NCAR have mentioned it too. It has always happened when a user > has left background processes running after logout. The process seems > like it doesn't want to release the ttypx and as you say, the workaround > is to leave the rlogin process going and then rlogin on another pseudo > tty. Also Sun says they cannot dupicate it. Maybe we should gang up on > Sun : -). I think I will at least call them back and say that I am not the > only one out here experiencing this prob. We have also seen this happen. Pseudo tty is reserved so, that when logging in it appears to be in raw mode although stty says it is normal. Using newline I am able to log in but all characters get mapped to EOF so it does not help, as I get immediately logged out. But when user with tcsh as login shell logs in, pseudo tty appears to work ok. And everytime this happens, there has been background processes on that line. Pertti Lehtinen pl@tut.fi pl@tut.fi Pertti Lehtinen Tampere University of Technology Software Systems Laboratory
thorstad@wooglin.scc.com (Brian Thorstad) (03/08/89)
I also have a problem with rlogins hanging.... I have several Sun386i's, and occasionally a login just hangs. Tracing the csh session on the remote side reveals that it is working (reading characters & thinging about them), but is does NOT echo anything back to the screen. I found that a ^J (line feed??) is accepted as a line terminator, and can type commands (without echo) followed by a ^J. "exit^J" is what comes to mind :-). I have tried every stty option I could, but nothing seems to work. Any ideas? Brian Thorstad Contel Federal Systems (thorstad@wooglin.scc.com)
guy@uunet.uu.net (Guy Harris) (03/16/89)
>Pseudo tty is reserved so, that when logging in it appears to be in raw >mode although stty says it is normal. See my previous posting. The pseudo-tty is in "half-remote" mode; the posting includes a program that can take it out of that mode.