CronExpression fails to calculate properly next execution when running on the day of winter daylight saving time

[guilroux]

Affects: Spring Framework 5.3.16

The PR #28044 fixing the issue #28038 did cause a regression for winter daylight saving time

Problem: CronExpression fails to calculate properly next execution when running on the day of winter daylight saving time, just before DST is applied.

Here is a unit test case that you can add to CronExpressionTests#daylightSaving to reproduce the problem :

cronExpression = CronExpression.parse("0 5 0 * * *");

last = ZonedDateTime.parse("2019-10-27T01:05+02:00[Europe/Paris]");
expected = ZonedDateTime.parse("2019-10-28T00:05+01:00[Europe/Paris]");
actual = cronExpression.next(last);
assertThat(actual).isNotNull();
assertThat(actual).isEqualTo(expected);

Please note that in the previous version 5.3.15 everything worked fine for that case

[poutsma]

@guilroux Thank you for spotting this, without it users would have had invalid cron executions in October.

I have completely revised the way CronExpression rolls forward temporal units, see 7e2106b

Let me know if you see additional issues with this implementation, or have other concerns.

[mf81bln]

@poutsma

We had an issue with Spring Boot 2.6.4 / Framework 5.3.16 on DST switch yesterday (March 27)
We're using a simple TaskScheduler bean and a method annotated with @Scheduler(cron = "0 30 2 * * ?")

The execution was just skipped when time was jumping from 2am to 3am. I've tried to...

• add the time zone to the taskScheduler

    @Bean
    public TaskScheduler taskScheduler(final TaskSchedulerBuilder taskSchedulerBuilder)
    {
        return taskSchedulerBuilder
            .poolSize(10)
            .customizers(taskScheduler -> taskScheduler.setClock(Clock.system(ZoneId.of("Europe/Zurich"))))
            .build();
    }

• add zone property to @Scheduled

    @Scheduled(cron = "0 30 2 * * ?", zone = "Europe/Zurich")
    public void run() { ... }

Both didn't work - tried it by resetting system time to 01:59:30am.

During debugging I found CronTrigger.nextExecutionTime() always returning 2022-03-28T02:30:00+02:00
Is there anything else I have to configure so that the execution is not just skipped? Or do I need a custom handling for this?

I've checked documentation as well as previous issues / fixes and couldn't find any specifics on how to properly handle this scenario where an execution falls into the "skipped" time frame between 2am ... 3am

// edit:
I've also tried it with the newest versions Spring Boot 2.6.5 / Framework 5.3.17 (because this was fixed) and resetting the time of my machine to March 27, 01:59:30 - the execution was skipped again

[poutsma]

@mf81bln Please create a new issue instead of commenting on older, resolved issues. Feel free to ping me on said new issue.

FWIW, this works fine for me:

cronExpression = CronExpression.parse("0 30 2 * * ?"); // 01:59:30am
last =     ZonedDateTime.parse("2022-03-26T01:59:30+01:00[Europe/Zurich]");
expected = ZonedDateTime.parse("2022-03-26T02:30:00+01:00[Europe/Zurich]");
actual = cronExpression.next(last);
assertThat(actual).isEqualTo(expected);

[mf81bln]

@poutsma Sorry and thanks for your answer, I've created a new issue 👍

Your example works because it's running on March 26, switch to DST happened on Sunday, March 27