Handling Daylight Savings
The Scheduler makes use of the ZonedDateTime classes in the JDK to perform date/time calculations specific
to time zone regions. It is therefore necessary for the JDK to be always patched to the latest version, to ensure the latest
time zone data is used by the Scheduler.
To better understand the behavior of the Scheduler around Daylight Savings, see the example below.
Timezone Region – Chicago, Illinois, USA
-
On Mar 10th, 2024, the clock is adjusted after 1:59:59 AM to 3:00 AM, thereby moving an hour ahead. There is therefore, no 2AM on Mar 10th (Chicago).
-
On Nov 5th, 2023, the clock is adjusted after 1:59:59 AM back to 1:00 AM, thereby moving an hour back. Therefore, the times between 1 AM and 2 AM occur twice on this day.
Let us consider, the following tasks scheduled at these times (CST)
-
Task 1 – 12:30 am
-
Task 2 – 1:00 am
-
Task 3 – 1:30 am
-
Task 4 – 2:00 am
-
Task 5 – 2:30 am
-
Task 6 – 3:00 am
| Task - Date | Mar 9th | Mar 10th | Nov 4th | Nov 5th |
|---|---|---|---|---|
|
Task 1 (Chicago) |
12:30 AM |
12:30 AM |
12:30 AM |
12:30 AM |
|
Task 1 (UTC) |
6:30 AM |
6:30 AM |
5:30 AM |
5:30 AM |
|
Task 2 (Chicago) |
1:00 AM |
1:00 AM |
1:00 AM |
1:00 AM |
|
Task 2 (UTC) |
7:00 AM |
7:00 AM |
6:00 AM |
6:00 AM |
|
Task 3 (Chicago) |
1:30 AM |
1:30 AM |
1:30 AM |
1:30 AM |
|
Task 3 (UTC) |
7:30 AM |
7:30 AM |
6:30 AM |
6:30 AM |
|
Task 4 (Chicago) |
2:00 AM |
3:00 AM |
2:00 AM |
2:00 AM |
|
Task 4 (UTC) |
8:00 AM |
8:00 AM |
7:00 AM |
8:00 AM |
|
Task 5 (Chicago) |
2:30 AM |
3:30 AM |
2:30 AM |
2:30 AM |
|
Task 5 (UTC) |
8:30 AM |
8:30 AM |
7:30 AM |
8:30 AM |
|
Task 6 (Chicago) |
3:00 AM |
3:00 AM |
3:00 AM |
3:00 AM |
|
Task 6 (UTC) |
9:00 AM |
8:00 AM |
8:00 AM |
9:00 AM |
Daylight Time start
– Moves forward an hour
Daylight Time ends – Moves back an hour