Prisma ORM Error P2024: Connection pool timeout

Identify: does your log match?

PrismaClientKnownRequestError:
Invalid `prisma.order.findMany()` invocation:

Timed out fetching a new connection from the connection pool. More info: http://pris.ly/d/connection-pool (Current connection pool timeout: 10, connection limit: 5)
  code: 'P2024',
  meta: { modelName: 'Order', connection_limit: 5, timeout: 10 }

1. High

   Many PrismaClient instances

   Instantiating PrismaClient per request or on every hot reload creates a new pool each time. Connections pile up while each pool stays small.

2. High

   Pool too small for concurrency

   Default connection_limit is num_cpus × 2 + 1; in a 1-vCPU container that is 3. Promise.all over 50 queries queues behind 3 connections.

3. Medium

   Slow queries hold connections

   A missing index or long interactive $transaction keeps connections checked out, starving other requests.

Fix

// lib/db.ts
import { PrismaClient } from '@prisma/client';
export const prisma = new PrismaClient();

// lib/db.ts
import { PrismaClient } from '@prisma/client';

const globalForPrisma = globalThis as unknown as { prisma?: PrismaClient };

export const prisma = globalForPrisma.prisma ?? new PrismaClient();

if (process.env.NODE_ENV !== 'production') globalForPrisma.prisma = prisma;

Verify: reproduce it on purpose

$ DATABASE_URL="$DATABASE_URL?connection_limit=1&pool_timeout=2" node -e "const {PrismaClient}=require('@prisma/client');const p=new PrismaClient();Promise.all([...Array(5)].map(()=>p.\$queryRaw\`SELECT pg_sleep(3)\`)).catch(e=>console.log(e.code))"

Prevent

• Never call new PrismaClient() inside a request handler.
• Batch with Promise.all in chunks no larger than connection_limit.
• Enable Prisma metrics to watch prisma_pool_connections_busy.