[BUG] - Job's NextRun time is inaccurate. The job has already run, but NextRun has not been updated to the next scheduled time.

[ThinkingXuan]

Describe the bug

Job's NextRun time is inaccurate. The job has already run, but NextRun has not been updated to the next scheduled time.

Multiple Jobs run into this situation when executing simultaneously.

// create a scheduler
	scheduler, err := gocron.NewScheduler()
	if err != nil {
		log.Fatal(err)
	}

	// add a job to the scheduler
	job1, err := scheduler.NewJob(
		gocron.DurationJob(1*time.Minute),
		gocron.NewTask(func() {
			log.Println("Job executed start")
			time.Sleep(10 * time.Second)
			log.Println("Job executed")
		}),
		gocron.WithName("example-job"),
		gocron.WithTags("important"),
	)

	// add a job to the scheduler
	job2, err := scheduler.NewJob(
		gocron.DurationJob(2*time.Minute),
		gocron.NewTask(func() {
			log.Println("Job executed start")
			time.Sleep(10 * time.Second)
			log.Println("Job executed")
		}),
		gocron.WithName("example-job"),
		gocron.WithTags("important"),
	)

	job3, err := scheduler.NewJob(
		gocron.DurationJob(3*time.Minute),
		gocron.NewTask(func() {
			log.Println("Job executed start")
			time.Sleep(10 * time.Second)
			log.Println("Job executed")
		}),
		gocron.WithName("example-job"),
		gocron.WithTags("important"),
	)

	job4, err := scheduler.NewJob(
		gocron.DurationJob(4*time.Minute),
		gocron.NewTask(func() {
			log.Println("Job executed start")
			time.Sleep(10 * time.Second)
			log.Println("Job executed")
		}),
		gocron.WithName("example-job"),
		gocron.WithTags("important"),
	)

	if err != nil {
		log.Fatal(err)
	}

	// start the scheduler
	scheduler.Start()

Version

gocorn: v2.18.2
go: 1.24.10

[iyashjayesh]

Thanks for the report! I tried reproducing this. Seems like the issue is that nextScheduled isn't being updated atomically when multiple jobs run concurrently, it's a race condition in the state management. I'll investigate the executor's job completion logic and get a fix out.

@JohnRoesler Please correct if my understanding is incorrect