Fix periodic tasks running twice the day after DST (Fix #1604)#4403
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thedrow merged 1 commit intocelery:masterfrom Nov 27, 2017
Merged
Fix periodic tasks running twice the day after DST (Fix #1604)#4403thedrow merged 1 commit intocelery:masterfrom
thedrow merged 1 commit intocelery:masterfrom
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…elery#1604) When computing the remaining time after DST change, last_run_at time was localized in the previous time zone (before DST) The resulting end date was then also localized in the previous time zone In case UTC offets are different, Replace tzinfo with the current one
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vbarbaresi
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Oct 17, 2018
…elery#1604) (celery#4403) When computing the remaining time after DST change, last_run_at time was localized in the previous time zone (before DST) The resulting end date was then also localized in the previous time zone In case UTC offets are different, Replace tzinfo with the current one (cherry picked from commit 89b0b46)
Photonios
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Feb 21, 2019
…elery#1604) (celery#4403) When computing the remaining time after DST change, last_run_at time was localized in the previous time zone (before DST) The resulting end date was then also localized in the previous time zone In case UTC offets are different, Replace tzinfo with the current one
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Description
The issue was with celery running with UTC enabled, and a timezone with DST.
When computing the remaining time after DST change,
last_run_attimewas localized in the previous time zone (before DST)
The resulting end date was then also localized in the previous time zone.
So the task was running two times (running an hour early, then on the correct time)
In case the DST was starting the night before, the task was running an hour late the day after.
Proposed fix
Use the relevant time zone to compute the remaining time:
in case UTC offets are different between now and the previous run, replace tzinfo of the previous run with the current one.
There could be undesirable side-effects: if we change timezone settings with the database scheduler. But this wasn't supported anyway and required a reset.