bugGNU Screen - Bugs: bug #27411, Screen freezes for long periods of...


bug #27411: Screen freezes for long periods of time, sometimes crashes

Submitter:  Justin Wells <jwells>
Submitted:  Wed 09 Sep 2009 02:53:05 PM UTC
Votes:  100  
Category:  Crash/Freeze/Infloop Severity:  3 - Normal
Priority:  * 5 - Normal Status:  Wont Fix
Privacy:  Public Assigned to:  None
Open/Closed:  Closed Release:  None
Fixed Release:  None Planned Release:  None
Work Required:  None
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Thu 04 Jun 2015 12:04:31 AM UTC, comment #4: 

It looks exactly like our "nonblock". It's not a bug.

From man-page:
nonblock [on|off|numsecs]

Tell  screen  how to deal with user interfaces (displays) that cease to accept output. This can happen if a user presses ^S or a TCP/modem connection gets cut but no hangup is received. If nonblock is off (this is the default) screen waits until the display restarts to accept the output.  If  nonblock is on, screen waits until the timeout is reached (on is treated as 1s). If the display  still  doesn't  receive  characters, screen will consider it "blocked" and stop sending characters to it. If at some time it restarts to accept characters, screen will unblock  the display and redisplay the updated window contents.

So, after a while (about 10-15 minutes) screen is available again for reconnection, but I can't reproduce "crashes" in this scenario.

I will close now this bugreport. If you can reproduce it (crashes) again (in new versions), please reopen this bugreport or create new one.

Alexander Naumov <anaumov>
Project Administrator
Fri 18 Jun 2010 09:31:28 AM UTC, comment #3: 

Welll... Dont't try this also... Either it dosen't work or my other less'es in screen's screens cause this...

Fri 18 Jun 2010 07:00:34 AM UTC, comment #2: 

Try this also:
1) Login using PuTTy (latest version) from Windows XP
2) Run screen
3) Pipe something into less (didin't try it with stand-alone less)
4) Lock the srcreen
5) Unlock the screen
6) Meditate about the locked session.
7) Close PuTTy
8) Login with PuTTy again
9) Try to reattach the frozen session
10) Meditate again.

Thu 01 Apr 2010 01:31:48 AM UTC, comment #1: 

We have been experiencing this problem with Debian (etch, and its prior edition).

1) SSH to a machine B from A via WLAN. 
2) Start a long running process from Screen and detach the process. 
3) B gradually goes out of WLAN range.
4) Only once in a while, say 5-10% of the time, the process freezes, either by the Screen or the process itself, for 5, 10, 20 minutes.

Note that, after #2, Screen or the SSH session is not explicitly terminated by the operator.

Sachko Honda <pickledplum>
Wed 09 Sep 2009 02:53:05 PM UTC, original submission:  

This bug has been closed, but I see this behavior quite often:


I am running "Screen version 4.00.03 (FAU) 23-Oct-06" on Debian etch. I connect using ssh (specifically putty) to long-running screen sessions (other reports I have found indicate this is significant).

A couple of times a day I see a screen window temporarily freeze. It will be just one window within the screen session, I can still create new windows, switch between screen windows, and work in other screen windows. Usually the frozen window will eventually recover. I am not sure how long it takes to recover, but it appears to be many minutes, maybe 5 or 10 or even 20.

Once the frozen window recovers any keystrokes I entered into the frozen window will appear and everything will be normal again.

If I attempt to kill the frozen window using the 'K' window kill feature screen becomes highly unstable and crashes. If I do nothing in some cases screen will still crash, but this is quite rare. Generally it will recover without any other issue if I wait for a very long time.

What could I do to assist in debugging this? Is there some logging I could enable, or other information I could collect, which would help screen developers to figure this one out?

I can see that it has been reported before by others but that the screen development team has not been able to replicate the issue. I am willing to help out if there is something I could do to help resolve the issue.

Justin Wells <jwells>


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  • -email is unavailable- added by anaumov (Posted a comment)
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  • -email is unavailable- added by jwells (Voted in favor of this item)
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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2015-06-04 anaumov StatusNone Wont Fix
        Open/ClosedOpen Closed
    2010-07-13 ohnobinki Carbon-Copy- Added ohnobinki
    2009-11-02 jwells Carbon-Copy- Added jwells

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