Daylight Savings Time Tips

Best Practices for Quartz Scheduler : Daylight Savings Time Tips

Avoid Scheduling Jobs Near the Transition Hours of Daylight Savings Time

Note:

For specifics of the transition hour and the amount of time the clock moves forward or back varies by locale, see: https://secure.wikimedia.org/wikipedia/en/wiki/Daylight_saving_time_around_the_world.

SimpleTriggers are not affected by Daylight Savings Time as they always fire at an exact millisecond in time, and repeat an exact number of milliseconds apart.

Because CronTriggers fire at given hours/minutes/seconds, they are subject to some oddities when DST transitions occur.

As an example of possible issues, scheduling in the United States within time zones/locations that observe Daylight Savings time, the following problems may occur if using CronTrigger and scheduling fire times during the hours of 1:00 AM and 2:00 AM:

1:05 AM may occur twice, thus duplicate firings on CronTrigger are possible

2:05 AM may never occur, thus missed firings on CronTrigger are possible

Again, specifics of time and amount of adjustment varies by locale.

Other trigger types that are based on sliding along a calendar (rather than exact amounts of time), such as CalenderIntervalTrigger, will be similarly affected. However, rather than missing a firing, or firing twice, these trigger type might end up having their fire time shifted by an hour.

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