Serverless function timeout from synchronous operations

Serverless functions timeout in production. Works locally but times out deployed. Common with database connections and external API calls.

Common causes: (1) Cold DB connections — reuse between invocations, use RDS Proxy. (2) DNS resolution in VPC. (3) External API hanging — set explicit timeouts with AbortController. (4) Large payload — use streaming or queue. (5) Connection pool exhaustion — use minimal pool size. (6) Increase function timeout.

Serverless functions have hard timeout limits. Every external call must have its own timeout shorter than the function timeout.