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Date: Thu, 17 Dec 2009 15:11:19 -0700
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Subject: Re: Cygwin 1.7 GNU screen freezing when disconnected
From: Karim Ali <khadgar34+cygwin AT gmail DOT com>
To: cygwin AT cygwin DOT com
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On Thu, Dec 17, 2009 at 1:06 PM, Andrew Schulman wrote:
> Karim, I'm afraid that I don't have much to offer here. =C2=A0A few thoug=
hts:
>
> After you kill ssh, what does screen -list say?

After I kill ssh, screen -list doesn't do anything. It basically
becomes unresponsive as well.

> You probably know that when you're connected to a screen session, there a=
re
> two screen processes, which communicate with each other through a socket.
> When you detach, the foreground screen process exits but the background o=
ne
> stays around, waiting for a new attach. =C2=A0It seems that when you kill=
 ssh,
> somehow data stops flowing to or from the background screen process from
> that socket. =C2=A0And that unfortunately is about as deep as my knowledg=
e of
> screen goes.
>
> strace can probably point to the problem, although I don't know if I have
> the ability to find it. =C2=A0Others on this list probably can. =C2=A0I w=
ould think
> of looking at strace output for the following:
>
> * the background screen process (i.e., the one that stays running when you
> detach from it) at the time you kill ssh, especially compared to when you
> detach from it normally.
>
> * the foreground and background screen processes when you try to reattach
> after having killed ssh. =C2=A0Again this might be most useful when compa=
red to
> a successful reattach after a normal detach.
>
> If you post or link to this, I'll take a look and maybe I or someone else
> can find the problem.

I'm sorry, I'm not really sure how to use strace. What I am currently
doing is (for the background process):
- Run screen, detach from the screen session
- Find the PID of the remaining screen process
- Attach to it with strace using: strace -o screen_bg -p <PID>
- Attach to the screen session, detach, reattach and then run 'exit'
in the session

After I do this strace has ended and the screen_bg file has no output
in it. Is there something I'm doing wrong or is this normal?

Thanks,
Karim

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