Spring Boot Schedulers Job – Real-World Examples & Guide

In many applications, we need to run background jobs — like sending reminders, syncing data, or cleaning logs. Spring Boot provides a very simple way to schedule such tasks using the @Scheduled annotation.

🚀 Enable Scheduling in Spring Boot

Just add @EnableScheduling in your main class:

@SpringBootApplication
@EnableScheduling
public class CodingBootApplication {
    public static void main(String[] args) {
        SpringApplication.run(CodingBootApplication.class, args);
    }
}

@SpringBootApplication
@EnableScheduling
public class CodingBootApplication {
    public static void main(String[] args) {
        SpringApplication.run(CodingBootApplication.class, args);
    }
}

🛠️ Example 1: Run Task Every 10 Seconds

@Component
public class MyScheduler {

    @Scheduled(fixedRate = 10000) // runs every 10 sec
    public void printMessage() {
        System.out.println("Running scheduled task at " + LocalDateTime.now());
    }
}

@Component
public class MyScheduler {

    @Scheduled(fixedRate = 10000) // runs every 10 sec
    public void printMessage() {
        System.out.println("Running scheduled task at " + LocalDateTime.now());
    }
}

fixedRate = 10000 → runs the task every 10 seconds after the previous start

🕒 Example 2: Run Task Daily at 2 AM (Using Cron)

@Component
public class DailyJobScheduler {

    @Scheduled(cron = "0 0 2 * * *")
    public void runDailyJob() {
        System.out.println("Running daily cleanup at 2 AM");
    }
}

@Component
public class DailyJobScheduler {

    @Scheduled(cron = "0 0 2 * * *")
    public void runDailyJob() {
        System.out.println("Running daily cleanup at 2 AM");
    }
}

📌 Cron Format in Spring (6 fields):

second minute hour day-of-month month day-of-week

Example: 0 0 2 * * * → at 2:00:00 AM every day

second: 0–59

minute: 0–59

hour: 0–23

day-of-month: 1–31

month: 1–12 (or JAN–DEC)

day-of-week: 0–6 (or SUN–SAT), where 0 = Sunday

🔁 Common Cron Examples:

Every 5 minutes:0 */5 * * * *
Every 30 minutes:0 */30 * * * *
Every hour at 15th minute:0 15 * * * *
Every day at midnight:0 0 0 * * *
Every Monday at 8:30 AM:0 30 8 * * MON

🧹 Example 3: Cleanup Task Every Midnight

@Component
public class CleanupScheduler {

    @Scheduled(cron = "0 0 0 * * ?")
    public void clearTempFiles() {
        // pretend to delete temp files
        System.out.println("[Midnight Cleanup] Temp files cleared");
    }
}

@Component
public class CleanupScheduler {

    @Scheduled(cron = "0 0 0 * * ?")
    public void clearTempFiles() {
        // pretend to delete temp files
        System.out.println("[Midnight Cleanup] Temp files cleared");
    }
}

📦 YAML-Based Control (Recommended)

Instead of hardcoding cron in code, read it from application.yml:

scheduler:
  cleanup:
    cron: "0 0 0 * * ?"

scheduler:
  cleanup:
    cron: "0 0 0 * * ?"

Now use:

@Component
@RequiredArgsConstructor
public class ConfigurableScheduler {

    private final Environment environment;

    @Scheduled(cron = "#{'${scheduler.cleanup.cron}'}")
    public void run() {
        System.out.println("[YAML Scheduler] Running at configured time");
    }
}

@Component
@RequiredArgsConstructor
public class ConfigurableScheduler {

    private final Environment environment;

    @Scheduled(cron = "#{'${scheduler.cleanup.cron}'}")
    public void run() {
        System.out.println("[YAML Scheduler] Running at configured time");
    }
}

🔄 fixedDelay vs fixedRate vs Async in spring boot scheduler jobs

Attribute	Behavior
`fixedRate`	Runs every X ms from start time
`fixedDelay`	Runs every X ms after previous completes

@Scheduled(fixedDelay = 5000) // runs after 5 sec of last execution end

💡 What happens if your task takes long time?

Let’s say your task takes 15 seconds to complete.

With fixedRate = 10000 // we can also write 10_000 for readability (10 sec):
- The second execution will start even if the previous one is not finished.
- This may result in overlapping executions if the task is slow.
With fixedDelay = 10000 // we can also write 10_000 for readability:
- It will wait for the current task to finish.
- Then wait 10 sec, then run again.
- This is safer for long-running jobs.
With cron expression:
- Cron triggers the task at the exact specified time, even if the previous task is still running.
- So if your job takes longer than the cron interval, you may get multiple overlapping executions.
- Spring does not stop or queue it. You must manually handle overlaps if needed.
With @Async:
- If you annotate your scheduled method with @Async, it runs in a separate thread.
- This is useful when you don’t want the main thread to wait.
- But it also means your job runs in parallel, so you need to handle overlaps or shared resource issues manually.
Example:@Async @Scheduled(fixedRate = 10000) public void runAsyncJob() { // runs asynchronously every 10 seconds }
- Also add @EnableAsync in your main config class.
@SpringBootApplication @EnableAsync @EnableScheduling public class AppMain {}

🔁 What Happens in Multiple App Instances?

If your Spring Boot app is running in a cluster or has multiple pods/instances, then:

Each instance will execute the scheduled task independently.
That means if 3 instances are running, your task will run 3 times at same time.

💡 To avoid duplicate runs in such setup:

Use distributed locks (like Redis-based lock or DB-based lock)
Example: ShedLock — popular lib to manage single-instance execution

⚠️ Common Mistakes in spring boot schedulers job

❌ Forgetting @EnableScheduling
❌ Using @Scheduled on private methods (must be public)
❌ Cron format mismatch (watch day-of-week and month)
❌ Not handling overlaps in multi-instance deployments

❗ Error Handling in Spring boot Schedulers job

If a scheduled method throws an exception and it’s not caught, it may silently fail or stop future executions in some thread pools.

To prevent this, always wrap your logic inside a try-catch block:

@Scheduled(fixedDelay = 10000)
public void runTask() {
    try {
        // your business logic
    } catch (Exception e) {
        log.error("Scheduled job failed", e);
        // optionally send alert/email/slack notification
    }
}

@Scheduled(fixedDelay = 10000)
public void runTask() {
    try {
        // your business logic
    } catch (Exception e) {
        log.error("Scheduled job failed", e);
        // optionally send alert/email/slack notification
    }
}

🧪 Testing Scheduled Jobs

You can reduce the delay time in @Scheduled while testing locally (like 2-3 seconds).
If your job depends on DB or services, consider mocking them to isolate logic.
Unit testing can be done by extracting the logic into a separate service method.

🚫 Disabling or Controlling Jobs via Config

Sometimes you don’t want a scheduler to run in a certain environment (like staging or test). You can control it from application.yml:

scheduler:
  enabled: false

scheduler:
  enabled: false

Use this with @ConditionalOnProperty:

@Component
@ConditionalOnProperty(name = "scheduler.enabled", havingValue = "true")
public class MyConditionalJob {

    @Scheduled(cron = "0 0 1 * * *")
    public void run() {
        System.out.println("Running only if enabled=true in config");
    }
}

@Component
@ConditionalOnProperty(name = "scheduler.enabled", havingValue = "true")
public class MyConditionalJob {

    @Scheduled(cron = "0 0 1 * * *")
    public void run() {
        System.out.println("Running only if enabled=true in config");
    }
}

📊 Monitoring Spring boot Schedulers job

If you’re running jobs in production, it’s good to send trace logs to tools like:

📈 Splunk
📊 Kibana
📬 Email or Slack (for alerts)

You can also use MDC or logging frameworks to include trace IDs:

MDC.put("traceId", UUID.randomUUID().toString());
log.info("Job started");

MDC.put("traceId", UUID.randomUUID().toString());
log.info("Job started");

This helps in tracking logs when multiple jobs are running.

📚 Reference

Spring Scheduled Task Documentation

✅ Summary

Use @Scheduled for simple job scheduling in Spring Boot
Understand difference between fixedRate, fixedDelay, and cron
If job runs long, prefer fixedDelay
If deploying on multiple servers, ensure one instance runs the job using locking (like ShedLock)
YAML-based cron expressions give you config flexibility

CodingbootBlog