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HenriWahl / dhcpy6d

MAC address aware DHCPv6 server written in Python
https://dhcpy6d.de
GNU General Public License v2.0
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Debian: Two dhcpy6d instances are spawned #20

Closed FelixJacobi closed 5 years ago

FelixJacobi commented 5 years ago

I recently noticed that sometimes are two instances of dhcpy6d are spawned on Debian (using systemd as init system).

This leads to a lot of log spam (~600GB last time) like this:

Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address Jan 28 05:06:39 iserv.stsbl.de dhcpy6d[19458]: UNIQUE constraint failed: leases.address

Is there someone else who already noticed that or am I the first/only one?

HenriWahl commented 5 years ago

Interesting... is this reproducible? I never noted such behaviour. Maybe there are some systemd-directives for the .service file which avoid this?

Edit: See https://www.freedesktop.org/software/systemd/man/systemd.service.html#Type=

HenriWahl commented 5 years ago

Do you have some other component running which might be starting a second dhcpy6d?

FelixJacobi commented 5 years ago

Do you have some other component running which might be starting a second dhcpy6d?

As far as I know: No.

I took a closer look on it: There is no second process, Maybe I was fooled by htop which has shown two processes, I checked with pgrep and ps, according to them there was only one process for dhcpy6d. Also systemctl status told me so. Either the second process did never exists or was a very short living one... But if I runned kill on the second PID which wasn't shown by the systemctl, it said that it was killed. But after that, both instances were dead. Is there something in dhcpy6d which is actually forking? Just starting a second process does not seems to be a real problem, as the error is not shown. Is it possible to enable advanced logging somehow to get further context for the error?

Interesting... is this reproducible? I never noted such behaviour.

Did not see the issue on a different machine, but seems to periodically happen on the same one.

HenriWahl commented 5 years ago

Dhcpy6d runs several threads which might appear as several instances. On my system I count even 7 when looking at them via htop. So I guess the "UNIQUE constraint failed: leases.address"-error has some other reason. Would be interesting which one... what database do you use?

FelixJacobi commented 5 years ago

store_config is currently set to none and store_volatile is set to sqlite.

HenriWahl commented 5 years ago

Does https://stackoverflow.com/questions/29037793/sqlite-integrityerror-unique-constraint-failed help? Is there something non-unique in your DB?

Edit: Apparently some address is doubled but should be unique.

HenriWahl commented 5 years ago

I modified storage.py to act in case of IntegrityErrors like MySQL and update an entry instead of inserting it. Please check latest unstable https://dhcpy6d.ifw-dresden.de/files/unstable/dhcpy6d_0.7.99-9_all.deb.

FelixJacobi commented 5 years ago

Thanks, I will try it.

FelixJacobi commented 5 years ago

As far I can see until now: The change seems to resolve the issue. I think, I will wait for a week and watch if it happen again.

FelixJacobi commented 5 years ago

Did not happen again. Thanks for the support.