Scheduled Tasks

Ensure scheduled tasks run once across multiple instances.

Problem

Solution

import { WithLock } from '@nestjs-redisx/locks';

@Injectable()
export class ScheduledTasksService {
  @Cron(CronExpression.EVERY_DAY_AT_MIDNIGHT)
  @WithLock({
    key: 'daily-report',
    ttl: 3600000,
    waitTimeout: 0,
    onLockFailed: 'skip',
  })
  async generateDailyReport(): Promise<void> {
    this.logger.log('Starting daily report');
    await this.reportService.generateDaily();
    this.logger.log('Daily report completed');
  }

  @Cron(CronExpression.EVERY_WEEK)
  @WithLock({ key: 'weekly-cleanup', ttl: 7200000, waitTimeout: 0, onLockFailed: 'skip' })
  async weeklyCleanup(): Promise<void> {
    await this.cleanupService.deleteOldRecords();
  }
}

TTL Guidelines

Task Duration	Recommended TTL
< 1 minute	2 minutes
1-5 minutes	10 minutes
5-30 minutes	1 hour
30+ minutes	2x expected duration

Failure Recovery

If a task crashes, the lock auto-releases after TTL:

T0: Instance A acquires lock
T1: Instance A crashes
T2: Lock TTL expires
T3: Next trigger, Instance B acquires lock

Next Steps

• Background Jobs — Event-driven processing
• Locks Reference — Full API