rsync /somedir work@backups::somearchive/ gets stuck in huge maildirs, rsync /somedir root@backups:/some/path/ works

[Herwig Wittmann]

hi,

i hope i'm not reporting something well-known; i tried to
understand the available bug tracking information. please excuse
me if my problem report should not meet your standards, but i
want to direct your attention to the following:

                 http://koffein.org/av/rsync-bugreport/


        problem report for rsync 2.6.9 on linux/IA32, 09 Dec 2006
                 Herwig Wittmann - Initials At Geizhals .at

         *******************************************************
         "chrooted rsync gets stuck in huge maildirs, retval 12"
         *******************************************************


(i'm not sure wheter an chroot() mechanism is invoked in my case,
or not, please see the mentioned URI which contains the used rsync.conf)


*) it seems that rsync runs using the chroot mechanism get stuck
    reproduceably and time out with return value 12 in Maildirs
    with > 60 000 (mostly small) files
    (at least when the transfer runs over a line with limited bandwith)

*) rsync runs started as superuser, without use of the chroot mechanism
    seem to work over the same line

*) the 16 Mbit/s line used for the rsync transfer was monitored
    continuously during the transfer with a running "ping", there was no
    packet loss and > 95% of the round trip times were < 20ms

*) + rsync 2.6.9 on linux/IA32 was used;
    + i have read http://rsync.samba.org/ftp/unpacked/rsync/NEWS
    + there should have been plenty of free disk space on both hosts
    + continuous monitoring did not show any network errors
    + i do not want to supply the generated core dump for security
      reasons, as there might be information disclosure problems


debug run, all mentioned files can be found in
      http://koffein.org/av/rsync-bugreport/
**********************************************


1) at 15:39, rsync was started as a daemon on host "backup":
backup:~# date
Sat Dec  9 15:39:45 CET 2006
backup:~# strace -ff -o rsyncdaemon.strace rsync --daemon --no-detach \
                  --port 5678  --config /etc/rsyncd.conf 2>rsync.out

this later generated the following files on rsync daemon host "backup":
-rw-r--r--  1 root root     5596 Dec  9 15:40 rsyncdaemon.strace
-rw-r--r--  1 root root 26039248 Dec  9 15:43 rsyncdaemon.strace.13629
-rw-r--r--  1 root root   960396 Dec  9 15:43 rsyncdaemon.strace.13682


2) at 15:40, i started the rsync client on rsyncclient host "morework":
strace -ff -o rsyncclient.strace rsync --rsync-path=/root/rsync-debug \
       --port 5678\
       --timeout=600 -avz --numeric-ids --delete \
       --password-file=/etc/rsyncd.work \
       /home/xxy work at backups::work/home/xxy/ \
       2> /root/rsyncdebug.err >> /root/rsyncdebug.out

this later generated the following files on rsyncclient host "morework":
-rw-r--r-- 1 root root 70955672 Dec  9 15:46 rsyncclient.strace
-rw-r--r-- 1 root root      256 Dec  9 15:46 rsyncdebug.err
-rw-r--r-- 1 root root    34200 Dec  9 15:42 rsyncdebug.out

3) at 15:42, rsync transferred the last file, then both sides start
to wait indefinitely in select() system calls. i waited for two more
minutes and then

4) at 15:44, i invoked on the client host:
morework:~# netstat > netstat-clienthost.txt

5) at 15:44, i invoked on the daemon host:
backup:~# netstat > netstat-daemonhost.txt
backup:~# kill -SEGV 13682; mv core core.13682
mv: cannot stat `core': No such file or directory
# okay, seems this did not generate a core dump for some reason
backup:~# kill -SEGV 13629 # no core dump either
backup:~# killall -SEGV rsync    # <<-- but this generated a core file:
-rw------- 1 root root   364544 Dec  9 15:54 core


Best regards,
Herwig