🗄️ DatabasesAmazonproduction

Redis connection pool exhausted: new client created per request in serverless

Fresh2 months ago

Mar 14, 20260 views

Confidence Score71%

71%

Problem

The application returns 'ECONNREFUSED' or 'max number of clients reached' errors under moderate load. The root cause is creating a new ioredis client inside each API route handler or Lambda function invocation. Each new client opens a fresh TCP connection to Redis. In serverless environments with high concurrency, dozens of connections are opened simultaneously, exhausting the Redis server's client limit.

Error Output

Error: connect ECONNREFUSED 127.0.0.1:6379
    at new Redis (/var/task/node_modules/ioredis/built/redis/index.js)

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1 Fix

Canonical Fix

High Confidence Fix

69% confidence88% success rate5 verificationsLast verified Mar 14, 2026

Create a Redis singleton and reuse it across all requests

Medium Risk

Creating a new ioredis client per request or Lambda invocation opens a new TCP connection each time. In serverless environments with high concurrency, this exhausts the Redis server client limit rapidly.

Trust Score

5 verifications

88% success

Create a module-level singleton

In lib/redis.ts:

typescript

import Redis from 'ioredis'

// Module-level — created once, reused across requests
const redis = new Redis(process.env.REDIS_URL!, {
  maxRetriesPerRequest: 3,
  connectTimeout: 5000,
  lazyConnect: true,
})

export default redis

For Next.js, use the global guard to survive hot reload

Prevent multiple instances during hot reload in development:

typescript

const globalForRedis = globalThis as unknown as { redis: Redis | undefined }
export const redis = globalForRedis.redis ?? new Redis(process.env.REDIS_URL!)
if (process.env.NODE_ENV !== 'production') globalForRedis.redis = redis

3
Monitor connection count
Check current connections:
bash
```
redis-cli INFO clients | grep connected_clients
```

Validation

Under load, redis INFO clients shows a stable connection count, not growing unboundedly.

Verification Summary

Worked: 5

Partial: 2

Failed: 1

Last verified Mar 14, 2026

Environment

Product: Redis (ioredis) + Serverless
Environment: production

Submitted by

Alex Chen

2450 rep