creating-client-singletons

P1017 errors occur when multiple PrismaClient instances exhaust the database connection pool. In serverless environments, each function invocation can create a new client. A singleton pattern ensures one shared PrismaClient across all invocations, preventing pool exhaustion.

Create a centralized module that exports a single PrismaClient instance using a global singleton pattern with globalThis or global. Replace all local client instantiations with imports from this module, ensuring every part of your application shares one connection pool.

Yes. Use globalThis to persist the PrismaClient across hot reloads, or implement module-level singletons that survive restart cycles. This prevents connection leaks and duplicate pools during development iteration.

A global singleton (globalThis) persists across module reloads in serverless and development, ideal for ephemeral environments. Module-level singletons work for traditional servers where modules load once; global approach provides stronger isolation in hot-reload scenarios.

Connection limits are optional but recommended. Configure connectionLimit in Prisma's datasource to cap pool size, preventing resource exhaustion. Logging can also help debug connection behavior in development and production.

Create a central client export file, update all imports to reference the singleton instead of creating new instances, and remove instantiation calls from route handlers and utility functions. This consolidates pool management into one entry point.