RunOnceAtStart sometimes it doesn't work.

[Kerwin1202]

Describe the bug

    scheduler.Schedule<Service>()
        .Cron("30 */2 * * *")
        .RunOnceAtStart()
        .Zoned(TimeZoneInfo.Local);

    scheduler.ScheduleAsync(async () =>
        {
             Console.WriteLine("Start refresh data");
           // ... other code 
        })
        .DailyAtHour(9)
        .RunOnceAtStart()
        .Zoned(TimeZoneInfo.Local);

public class Service : IInvocable
{
   ......  other code
    public async Task Invoke()
    {
        _logger. Information($"Start login {_config. UserName}");
        await Login();
    }
   ......  other code
}

Affected Coravel Feature
Scheduling

Expected behaviour
Output content immediately when starting the program. ( "Start login xxx" and "Start refresh data") , but when I run it many times, sometimes it does not output content, and the console does not report any error message.

run windows service.
.net core 7.0
coravel : 5.0.2.0

[arteny]

Not works for me in .net 8 with ScheduleAsync as well

[chris-rp]

This is still an issue in
.net8, coravel 5.0.4

Anything new on this issue?

[jamesmh]

No news on this yet. Will look to investigate soon. Not sure what's going on at first glance. Unless someone else has any idea by looking at the source?

[jamesmh]

Curious for those who reported this: what kind of machine was this on? A small container? Local machine with many threads?

I have an idea of a potential race condition causing this, but can't reproduce at all ATM.

[jamesmh]

Was able to reproduce via unit testing the suspect concurrency scenario. Fixed in 6.0.2!

[jamesmh]

Please re-open if you find the issue persists. It's still possible that the issue has some other causes related to the .NET lifecycle 🤷.

[arteny]

Still not works on my side with 6.0.2
from this breakpoint:

		Scheduler.ScheduleAsync(async () => { await updateExposure(); })
			.EveryFifteenSeconds()
			.RunOnceAtStart();

desitnation method is called after several seconds

[jamesmh]

🥲 Thanks @arteny - I'll have to take another gander at this.

[jamesmh]

@arteny It's possible that there's another task causing this one to be delayed. If you put this task first in the list of all schedule tasks, does it improve things?

[jamesmh]

For example:

                scheduler.Schedule(() => Thread.Sleep(10000)).EverySecond();
                scheduler.ScheduleAsync(async () => { await Task.Delay(1); Console.WriteLine("SHOULD GO FIRST"); })
                    .Hourly()
                    .RunOnceAtStart();

Because the first task is not returning a Task (e.g. not await/async) it hogs the thread. So the second task won't run until the first one completes (after 10 seconds....). So it "looks" like the second one doesn't run immediately upon start up, but it IS triggered properly. It's just that another task is not letting go of the thread.

That's what schedule workers are for. So this works:

                scheduler.Schedule(() => Thread.Sleep(10000)).EverySecond();
                scheduler.OnWorker("TEST");
                scheduler.ScheduleAsync(async () => { await Task.Delay(1); Console.WriteLine("SHOULD GO FIRST"); })
                    .Hourly()
                    .RunOnceAtStart();

This code will put the second scheduled task on it's own thread, so it's not blocked / waiting on the first task to complete.

It might be the case that everyone or some of you guys/gals are experiencing this issue. Otherwise, I cannot reproduce this issue at all, other than this approach.

So what I recommend for everyone having this issue is to either list these "run once at start" tasks first in your configuration (so they run first at run time) or put them on a dedicated worker.

Let me know this works for anyone or doesn't! Thanks!