Timeout

The Pattern

A timeout puts a deadline on every network call: if no answer arrives in time, the call is declared failed, and the resources it was holding are released.

It's the first rule of being on hold: decide up front how long you'll wait before hanging up. Software, strangely, often doesn't. Here's the uncomfortable default this pattern corrects: many clients wait forever. Python's popular requests library has no timeout unless you pass one. A raw TCP connection to a machine that silently died can hang for many minutes before the operating system gives up.