📦 Distributed Job Queue System (GoLang)

🧩 Problem Statement

Build a distributed, fault-tolerant, and extensible job queue system using Go. The system must handle asynchronous background tasks like sending emails, generating reports, etc., and must support retries, prioritization, scheduling, observability, and failure handling.

---

🎯 Goals

• RESTful API for job submission and status tracking
• Multiple worker support with concurrency
• Retry and dead-letter queue mechanism
• Job prioritization (high, medium, low)
• Delayed job scheduling
• Monitoring via Prometheus
• Optional: Admin UI dashboard

---

🔧 Tech Stack

Component	Tech
Language	Go
Queueing	Redis or PostgreSQL
API Framework	chi/gin
Monitoring	Prometheus + Grafana
Deployment	Docker, optional K8s

---

✅ Features

1. Job Producer API

POST /submit-job
{
  "type": "email",
  "payload": {"email": "[email protected]"},
  "priority": "high",
  "delay": 30
}

• Stores job in Redis (list/sorted set) or Postgres with run_at field

2. Worker Pool

• Goroutines fetch and execute jobs
• Configurable concurrency (e.g., 5 workers)

3. Retry + Dead Letter Queue

• Exponential backoff retry mechanism
• Max retries configurable (e.g., 3)
• Moves failed jobs to dead-letter queue with reason

4. Prioritization

• Use separate queues for priorities: job:high, job:medium, job:low
• Workers poll high priority queues first

5. Delayed Job Scheduling

• Scheduled jobs stored in Redis sorted set or Postgres run_at
• Mover service polls and enqueues ready jobs to live queues

6. Job Status Tracking

GET /job-status/:id

Returns job metadata, status, retries, and result

7. Admin Dashboard (Optional)

• View active, failed, and dead-letter jobs
• Retry/Resubmit failed jobs

8. Observability

• Prometheus metrics:
  • job_processing_duration_seconds
  • jobs_failed_total
  • jobs_processed_total
• Health check endpoint: /healthz

9. Scalability

• Multiple worker nodes supported
• Redis BLPOP or Postgres row locking to avoid duplicate processing

---

📘 Example Use Case

• User signup triggers /submit-job with type=email_welcome
• Worker picks the job, sends welcome email
• On failure, retries 3 times, then moves to dead-letter

---

📦 Optional Improvements

• CLI for job management (enqueue/retry/delete)
• Graceful shutdown and job requeue
• Dashboard built with Go templates or React
• Integration tests for full pipeline

---

Generated docs ( may be inaccurate )