TP14.4: Tareas Programadas

Objetivos del TP

• Configurar las tareas programadas
• Utilizar expresiones Cron
• Implementar informes automáticos
• Gestionar tareas asíncronas

Duración estimada: 45 min

---

Arquitectura

Application Spring Boot
    |
    +-- Scheduler Thread Pool
         |
         +-- Daily Report (0 0 6 * * *)
         +-- Hourly Cleanup (0 0 * * * *)
         +-- Price Sync (fixedRate = 60000)
         +-- Health Check (fixedDelay = 30000)

---

Parte 1: Configuración (10 min)

1.1 Aplicación

package com.example.scheduling;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.EnableAsync;

@SpringBootApplication
@EnableScheduling
@EnableAsync
public class SchedulingApplication {

    public static void main(String[] args) {
        SpringApplication.run(SchedulingApplication.class, args);
    }
}

1.2 Configuración

package com.example.scheduling.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;

@Configuration
public class SchedulingConfig implements SchedulingConfigurer {
    
    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.setTaskScheduler(taskScheduler());
    }
    
    @Bean
    public ThreadPoolTaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
        scheduler.setPoolSize(5);
        scheduler.setThreadNamePrefix("scheduler-");
        scheduler.setErrorHandler(t -> {
            System.err.println("Task error: " + t.getMessage());
        });
        return scheduler;
    }
}

1.3 application.yml

app:
  scheduling:
    enabled: true
  cleanup:
    max-age-hours: 24
  report:
    email: admin@example.com

---

Parte 2: Tareas Programadas (20 min)

2.1 Servicio de Tareas

package com.example.scheduling.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.concurrent.atomic.AtomicInteger;

@Service
public class ScheduledTaskService {
    
    private static final Logger log = LoggerFactory.getLogger(ScheduledTaskService.class);
    private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    
    private final AtomicInteger taskCounter = new AtomicInteger(0);
    
    // Cada 10 segundos
    @Scheduled(fixedRate = 10000)
    public void heartbeat() {
        int count = taskCounter.incrementAndGet();
        log.info("[Heartbeat #{}] Application is running at {}", 
            count, LocalDateTime.now().format(formatter));
    }
    
    // Cada 30 segundos después de finalizar la anterior
    @Scheduled(fixedDelay = 30000)
    public void cleanupTask() {
        log.info("[Cleanup] Starting cleanup task...");
        
        // Simular limpieza
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
        
        log.info("[Cleanup] Cleanup completed - {} items removed", 
            (int)(Math.random() * 100));
    }
    
    // Cada minuto (al inicio del minuto)
    @Scheduled(cron = "0 * * * * *")
    public void everyMinute() {
        log.info("[Cron] Minute task executed at {}", 
            LocalDateTime.now().format(formatter));
    }
    
    // Cada 5 minutos
    @Scheduled(cron = "0 */5 * * * *")
    public void everyFiveMinutes() {
        log.info("[Cron] Five-minute task executed");
        generateQuickReport();
    }
    
    // Todos los días a las 6 de la mañana
    @Scheduled(cron = "0 0 6 * * *")
    public void dailyReport() {
        log.info("[Daily] Generating daily report...");
        // Generar informe
        log.info("[Daily] Daily report generated and sent");
    }
    
    // Todos los lunes a las 9h
    @Scheduled(cron = "0 0 9 * * MON")
    public void weeklyReport() {
        log.info("[Weekly] Generating weekly report...");
    }
    
    private void generateQuickReport() {
        log.info("Quick report: Active threads = {}, Free memory = {} MB",
            Thread.activeCount(),
            Runtime.getRuntime().freeMemory() / (1024 * 1024));
    }
    
    // Método asíncrono
    @Async
    public void asyncTask(String taskName) {
        log.info("[Async] Starting async task: {} on thread {}", 
            taskName, Thread.currentThread().getName());
        
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
        
        log.info("[Async] Completed async task: {}", taskName);
    }
}

2.2 Servicio de Estadísticas

package com.example.scheduling.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.util.concurrent.atomic.AtomicLong;

@Service
public class StatisticsService {
    
    private static final Logger log = LoggerFactory.getLogger(StatisticsService.class);
    
    private final AtomicLong requestCount = new AtomicLong(0);
    private final AtomicLong errorCount = new AtomicLong(0);
    
    public void incrementRequests() {
        requestCount.incrementAndGet();
    }
    
    public void incrementErrors() {
        errorCount.incrementAndGet();
    }
    
    // Informe de estadísticas cada minuto
    @Scheduled(cron = "0 * * * * *")
    public void reportStatistics() {
        long requests = requestCount.getAndSet(0);
        long errors = errorCount.getAndSet(0);
        
        log.info("[Stats] Last minute: {} requests, {} errors, Error rate: {}%",
            requests,
            errors,
            requests > 0 ? (errors * 100 / requests) : 0);
    }
    
    // Verificación de salud cada 30 segundos
    @Scheduled(fixedRate = 30000)
    public void healthCheck() {
        Runtime runtime = Runtime.getRuntime();
        long usedMemory = (runtime.totalMemory() - runtime.freeMemory()) / (1024 * 1024);
        long maxMemory = runtime.maxMemory() / (1024 * 1024);
        int usagePercent = (int) (usedMemory * 100 / maxMemory);
        
        if (usagePercent > 80) {
            log.warn("[Health] High memory usage: {}% ({} MB / {} MB)", 
                usagePercent, usedMemory, maxMemory);
        } else {
            log.debug("[Health] Memory usage: {}% ({} MB / {} MB)", 
                usagePercent, usedMemory, maxMemory);
        }
    }
}

---

Parte 3: Controlador para Pruebas (10 min)

package com.example.scheduling.controller;

import com.example.scheduling.service.ScheduledTaskService;
import com.example.scheduling.service.StatisticsService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.Map;

@RestController
@RequestMapping("/api/tasks")
public class TaskController {
    
    private final ScheduledTaskService taskService;
    private final StatisticsService statisticsService;
    
    public TaskController(ScheduledTaskService taskService, 
            StatisticsService statisticsService) {
        this.taskService = taskService;
        this.statisticsService = statisticsService;
    }
    
    @PostMapping("/async/{name}")
    public ResponseEntity<Map<String, String>> triggerAsyncTask(@PathVariable String name) {
        taskService.asyncTask(name);
        return ResponseEntity.ok(Map.of(
            "message", "Async task '" + name + "' started",
            "status", "RUNNING"
        ));
    }
    
    @GetMapping("/simulate-traffic")
    public ResponseEntity<Map<String, String>> simulateTraffic(
            @RequestParam(defaultValue = "100") int requests) {
        
        for (int i = 0; i < requests; i++) {
            statisticsService.incrementRequests();
            if (Math.random() < 0.05) { // 5% errores
                statisticsService.incrementErrors();
            }
        }
        
        return ResponseEntity.ok(Map.of(
            "message", requests + " requests simulated"
        ));
    }
}

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Parte 4: Pruebas (10 min)

4.1 Observar los Logs

Inicie la aplicación y observe los logs:

[Heartbeat #1] Application is running at 2024-01-15 10:00:00
[Cron] Minute task executed at 2024-01-15 10:01:00
[Cleanup] Starting cleanup task...
[Cleanup] Cleanup completed - 45 items removed
[Stats] Last minute: 0 requests, 0 errors, Error rate: 0%

4.2 Probar las Tareas Async

# Disparar una tarea async
curl -X POST http://localhost:8080/api/tasks/async/test-task-1

# Simular tráfico
curl "http://localhost:8080/api/tasks/simulate-traffic?requests=500"

4.3 Verificar las Estadísticas

Espere 1 minuto y observe el informe de estadísticas en los logs.

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Expresiones Cron - Referencia

Expresión	Descripción
0 * * * * *	Cada minuto
0 */5 * * * *	Cada 5 minutos
0 0 * * * *	Cada hora
0 0 6 * * *	Todos los días a las 6h
0 0 9 * * MON	Todos los lunes a las 9h
0 0 0 1 * *	Primer día del mes

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Checklist de Validación

• Las tareas programadas se ejecutan
• Los logs muestran las ejecuciones
• Las tareas async funcionan
• Las estadísticas se calculan

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