[BackupPC-devel] BackupPC_Dump not reaping child processes when they finish.

[John R. <rou...@re...>]

Hi all:

I just installed BackupPC last night and I think I have an issue with
defunct processes caused by lack of a sigchld handler.

In my process table I see:

  backup    7186 28665 44 13:35 ?        00:05:30 /usr/bin/perl
     /tools/BackupPC-3.1.0beta0/bin/BackupPC_dump -f hostname

  backup    7279  7186  0 13:35 ?        00:00:00 [ssh] <defunct>
  backup    7344  7186  0 13:35 ?        00:00:03 [BackupPC_dump] <defunct>

  backup    7822  7186  0 13:36 ?        00:00:00 [ssh] <defunct>
  backup    7831  7186  0 13:36 ?        00:00:00 [BackupPC_dump] <defunct>

  backup    7837  7186  0 13:36 ?        00:00:00 /usr/bin/ssh -q -x -l
    root hostname /usr/bin/rsync --server --sender
    --numeric-ids --perms --owner --group -D --links --hard-links --times
    --block-size=2048 --recursive --one-file-system --checksum-seed=32761
    --ignore-times . /var/log/
  backup    7848  7186  0 13:36 ?        00:00:00 /usr/bin/perl
    /tools/BackupPC-3.1.0beta0/bin/BackupPC_dump -f hostname

It looks to me like the parent BackupPC_Dump (pid 7186) isn't wait(2)ing
for the child processes when it received a SIG_CHLD. I don't see a
child signal handler in the /tools/BackupPC-3.1.0beta0/bin/BackupPC_dump
file either.

The config that produces this is:

  $Conf{XferMethod} = 'rsync';

  $Conf{RsyncShareName} = [
    '/etc',
    '/var/bak',
    '/var/log',
    '/usr/local',
  ];

So it would appear the defunct backupPC_Dump and ssh pairs are from
the /etc and /var/bak backups and /var/log is running currently.

Can anybody confirm my diagnosis and add a SIGCHLD handler, or tell
why there shouldn't be one? Ultimately we will have some systems with
10 shares, and be running multiple hosts in parallel and this will
defintely trip the zombie process monitoring that we do as well as
looking bad and taking up space.

I didn't see any mention of this fix in the 3.1.0beta1 release notes,
so I assume the problem still exists. If people agree it's a bug, I'll
file it on sourceforge.

Some specs:

OS: centos 4.2
kernel: 2.6.9-42.0.10.ELsmp i686
BackupPC ver: 3.1.0beta0 

-- 
				-- rouilj

John Rouillard
System Administrator
Renesys Corporation
603-643-9300 x 111