block (or fix?) `tail -f`

[reidsunderland]

tail -f doesn't work well with dsh. It leaves the command running forever on the first server in the cluster.

There might be a way to make it work, but assuming there's not, we should block it because when done by accident it causes issues. (abandoned process using lots of CPU)

[andreleblanc11]

If you add a timeout inside of the executed dsh command it will automatically tear up the process after the timeout completes

dsh -c -M -m ddsr-ops01,ddsr-ops02 -- 'timeout 60 tail -f /local/home/sarra/.cache/sr3/log/sarra_cvt_fn_2bulletin_01.log'
ddsr-cmc-ops01: 2026-04-30 18:11:20,511 [DEBUG] sarracenia.flow filter B filtered incoming: 0, ok: 0 (directories: 0), rejected: 0, failed: 0 stop_requested: False have_vip: ['AnyAddressIsFine']
ddsr-cmc-ops01: 2026-04-30 18:11:20,511 [DEBUG] sarracenia.flow do processing 0 messages worked!
ddsr-cmc-ops01: 2026-04-30 18:11:20,576 [DEBUG] sarracenia.flow run  not throttling: limit: 0
ddsr-cmc-ops01: 2026-04-30 18:11:20,576 [DEBUG] sarracenia.flow run worked too long to sleep!
ddsr-cmc-ops01: 2026-04-30 18:11:20,577 [DEBUG] sarracenia.flow filter start len(incoming)=0, rejected=0
ddsr-cmc-ops01: 2026-04-30 18:11:20,577 [DEBUG] sarracenia.flow filter end len(incoming)=0, rejected=0
ddsr-cmc-ops01: 2026-04-30 18:11:20,577 [DEBUG] sarracenia.flow filter B filtered incoming: 0, ok: 0 (directories: 0), rejected: 0, failed: 0 stop_requested: False have_vip: ['AnyAddressIsFine']
ddsr-cmc-ops01: 2026-04-30 18:11:20,577 [DEBUG] sarracenia.flow do processing 0 messages worked!
ddsr-cmc-ops01: 2026-04-30 18:11:20,636 [DEBUG] sarracenia.flow run  not throttling: limit: 0
ddsr-cmc-ops01: 2026-04-30 18:11:20,636 [DEBUG] sarracenia.flow run sleeping for 5.00
ddsr-cmc-ops02: 2026-04-30 18:11:20,896 [DEBUG] sarracenia.flow filter B filtered incoming: 0, ok: 0 (directories: 0), rejected: 0, failed: 0 stop_requested: False have_vip: ['AnyAddressIsFine']
ddsr-cmc-ops02: 2026-04-30 18:11:20,897 [DEBUG] sarracenia.flow do processing 0 messages worked!
ddsr-cmc-ops02: 2026-04-30 18:11:20,960 [DEBUG] sarracenia.flow run  not throttling: limit: 0
ddsr-cmc-ops02: 2026-04-30 18:11:20,960 [DEBUG] sarracenia.flow run worked too long to sleep!
ddsr-cmc-ops02: 2026-04-30 18:11:20,961 [DEBUG] sarracenia.flow filter start len(incoming)=0, rejected=0
ddsr-cmc-ops02: 2026-04-30 18:11:20,961 [DEBUG] sarracenia.flow filter end len(incoming)=0, rejected=0
ddsr-cmc-ops02: 2026-04-30 18:11:20,961 [DEBUG] sarracenia.flow filter B filtered incoming: 0, ok: 0 (directories: 0), rejected: 0, failed: 0 stop_requested: False have_vip: ['AnyAddressIsFine']
ddsr-cmc-ops02: 2026-04-30 18:11:20,961 [DEBUG] sarracenia.flow do processing 0 messages worked!
ddsr-cmc-ops02: 2026-04-30 18:11:21,017 [DEBUG] sarracenia.flow run  not throttling: limit: 0
ddsr-cmc-ops02: 2026-04-30 18:11:21,017 [DEBUG] sarracenia.flow run sleeping for 5.00

...

date
Thu Apr 30 18:09:42 UTC 2026

ps aux | grep 'tail -f'
root     11661  0.0  0.0  12896   920 ?        Ss   18:08   0:00 timeout 60 tail -f /local/home/sarra/.cache/sr3/log/sarra_cvt_fn_2bulletin_01.log
root     11664 91.8  0.0   8660  2072 ?        R    18:08   0:54 tail -f /local/home/sarra/.cache/sr3/log/sarra_cvt_fn_2bulletin_01.log
root     17654  0.0  0.0  15584  1020 pts/4    S+   18:09   0:00 grep --color=always tail -f


date
Thu Apr 30 18:09:43 UTC 2026

ps aux | grep 'tail -f'
root     17739  0.0  0.0  15584  1052 pts/4    S+   18:09   0:00 grep --color=always tail -f