On 4/13/21 5:00 PM, Frank Cox wrote:
> On Tue, 13 Apr 2021 22:29:26 +0200
> Simon Matter wrote:
>
>> You could try running strace on the hanging process so see what it's doing.
> [frankcox@mutt temp]$ rsync -avv ../temp/ jeff:temp
> opening connection using: ssh jeff rsync --server -vvlogDtpre.iLsfxC . temp (7 args)
> sending incremental file list
> delta-transmission enabled
> abc is uptodate
> total: matches=0 hash_hits=0 false_alarms=0 data=0
>
> Leaving that sit there apparently doing nothing (but still not giving me my cursor back) I switched to another terminal window and did the following:
>
> [frankcox@mutt ~]$ ps -FA | grep rsync
> frankcox 5400 2435 0 60586 3160 5 14:52 pts/0 00:00:00 rsync -avv ../temp/ jeff:temp
> frankcox 5401 5400 0 67980 7440 1 14:52 pts/0 00:00:00 ssh
jeff rsync --server -vvlogDtpre.iLsfxC . temp
> frankcox 5526 5416 0 55476 1076 3 14:53 pts/1 00:00:00 grep --color=auto rsync
>
> [frankcox@mutt ~]$ strace -p 5401
> strace: Process 5401 attached
> select(11, [5 9 10], [], NULL, NULL
>
> Then it just sits there with no further action. I get my cursor back when I hit ctrl-c.
>
> [frankcox@mutt ~]$ strace -p 5400
> strace: Process 5400 attached
> restart_syscall(<... resuming interrupted nanosleep ...>) = 0
> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0
> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0
> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0
> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0
> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0
> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0
> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0
> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0
> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0
> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0
> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0
> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0
> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0
>
> The wait4-etc line just keeps repeating endlessly until I hit ctrl-c.
>
> Unfortunately, I have no idea what any of the above actually means. Does it tell us anything interesting?
Yay! I am glad someone else on the planet is experiencing this.
I noticed this started happening to me after updating some CentOS Linux 8
systems today.
I discovered if I set ForwardX11=no (either on ssh command line or in ~/.ssh/config) the hang does not happen. But why does that matter? No updates to openssh.
It is not the systemd update doing something silly with session management. I painfully downgraded manually and rebooted to no effect.
As an aside, why can't we we have nice things in life like 'dnf downgrade
systemd\*' actually work? I did the below - might be dumb, but it worked -- alternate suggestions to downgrade are appreciated - searching the list and my google-fu was off the mark today.
cd [path-to-repo]/centos/8/BaseOS/x86_64/os/Packages
dnf downgrade $(rpm -qa systemd\* | grep 239-41.el8_3.2 | sed -e 's/3\.2/3.1/' -e 's/^/.\//' -e 's/$/.rpm/')
Chris
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