should lock to avoid parallel invocation

[yarikoptic]

I had added an external harddrive, adjusted btrbk.conf to backup to it, and manually started btrbk run. Since it is the first invocation, it takes awhile to complete. Meanwhile cron job also invoked btrbk and now there are two of them dumping in parallel

yoh      3875614  0.0  0.0  16220  4816 pts/19   Ss+  Oct14   0:06  |   \_ zsh
yoh      2703946  0.0  0.0  16652  7052 pts/46   Ss   Oct19   0:17  |   \_ zsh
root     1790245  0.0  0.0   8684  3388 pts/46   S    Oct31   0:00  |   |   \_ sudo -s
root     1790246  0.0  0.0   9088  2632 pts/46   S    Oct31   0:00  |   |       \_ /bin/zsh
root     1790267  0.0  0.0  18352  4444 pts/46   S+   Oct31   0:00  |   |           \_ /usr/bin/perl /usr/sbin/btrbk run
root     1790285  0.0  0.0   2400   364 pts/46   S+   Oct31   0:00  |   |               \_ sh -c btrfs send /mnt/btrfs/.snapshots/home.20201022 | mbuffer -v 1 -q -m 512m | btrfs receive /mnt/backup/_btrbk/
root     1790286 98.2  0.0  12756   372 pts/46   Rl+  Oct31 784:07  |   |                   \_ btrfs send /mnt/btrfs/.snapshots/home.20201022
root     1790287  2.7  1.6 535012 525496 pts/46  Sl+  Oct31  22:02  |   |                   \_ mbuffer -v 1 -q -m 512m
root     1790288  5.0  0.0   4560  1872 pts/46   S+   Oct31  39:57  |   |                   \_ btrfs receive /mnt/backup/_btrbk/

root     1835428  0.0  0.0   2748  1764 ?        Ss   07:33   0:00 /usr/sbin/anacron -d -q -s
root     1835664  0.0  0.0   2400   580 ?        S    07:38   0:00  \_ /bin/sh -c run-parts --report /etc/cron.daily
root     1835665  0.0  0.0   2296   424 ?        S    07:38   0:00      \_ run-parts --report /etc/cron.daily
root     1835673  0.0  0.0   6604  1580 ?        S    07:38   0:00          \_ /bin/bash /etc/cron.daily/btrbk
root     1835674  0.0  0.0  18308 11412 ?        S    07:38   0:00              \_ /usr/bin/perl /usr/sbin/btrbk run
root     1835687  0.0  0.0   2400   652 ?        S    07:38   0:00                  \_ sh -c btrfs send /mnt/btrfs/.snapshots/home.20201023 | mbuffer -v 1 -q -m 512m | btrfs receive /mnt/backup/_btrbk/
root     1835688 98.7  0.0  12756   608 ?        Rl   07:38  91:55                      \_ btrfs send /mnt/btrfs/.snapshots/home.20201023
root     1835689  2.9  1.6 535012 525728 ?       Sl   07:38   2:46                      \_ mbuffer -v 1 -q -m 512m
root     1835690  7.7  0.0   4560  2020 ?        S    07:38   7:10                      \_ btrfs receive /mnt/backup/_btrbk/

$> ls -l /mnt/btrfs/.snapshots/
total 0
drwxr-xr-x 1 root root 218 Jul 31 14:44 home.20201022/
drwxr-xr-x 1 root root 218 Jul 31 14:44 home.20201023/
drwxr-xr-x 1 root root 218 Jul 31 14:44 home.20201024/
...

not sure how unkosher that would be.. I will interrupt cron one for now.

flock or alike could have been used to prevent cron invocation due to btrbk already being running

edit : killed cron job, disabled it for now, and removed /mnt/backup/_btrbk/home.20201023 since expect manually invoked btrbk to want to transmit the it later on

[joker-x]

You can set "lockfile" in btrbk config file:

https://github.com/digint/btrbk/blob/master/btrbk.conf.example#L81

[digint]

not sure how unkosher that would be.. I will interrupt cron one for now.

From a btrfs point of view, this should be kosher ;-)

[yarikoptic]

You can set "lockfile" in btrbk config file:

https://github.com/digint/btrbk/blob/master/btrbk.conf.example#L81

Thank you! I will!

IMHO locking should be default mode of operation, even if not explicitly specified, or explicitly disabled

[joker-x]

Yes, I think so too @yarikoptic