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Timeout

Category: Async · Status: stub · Lessons: chapter 06, Async (planned)

One line: Giving up on an operation after a time limit — which, in concurrent code, means cancelling or abandoning whatever was still running on its behalf.

Also called: deadline.

How it connects

flowchart LR
  n_cancellation["Cancellation"]
  n_deadlock["Deadlock"]
  n_timeout["Timeout"]
  n_timeout -->|prevents| n_deadlock
  n_timeout -->|uses| n_cancellation
  classDef center stroke-width:3px
  class n_timeout center
  classDef outside stroke-dasharray: 4 3
  class n_cancellation,n_deadlock outside

In each language
Rust Receiver::recv_timeout ↗ on a channel; tokio's time::timeout ↗ requires a future to complete before a duration has elapsed
Go context.WithTimeout ↗ for a whole call tree; time.After ↗ as one case of a select
C pthread_cond_timedwait ↗, which takes an absolute time
C++ std::future::wait_for ↗, which returns future_status::timeout
Java Future.get ↗ with a timeout throws TimeoutException; CompletableFuture.orTimeout ↗
Python asyncio.timeout ↗ cancels the task and turns the CancelledError into a TimeoutError; asyncio.wait_for ↗
C# CancellationTokenSource.CancelAfter ↗, and Task.WaitAsync ↗ with a TimeSpan
JavaScript AbortSignal.timeout() ↗ returns a signal that aborts with a TimeoutError
Kotlin withTimeout ↗ cancels its block with a TimeoutCancellationException; withTimeoutOrNull is the variant the guide ↗ uses
Erlang and Elixir an after clause on receive, in Erlang ↗ and Elixir ↗
Haskell System.Timeout.timeout ↗

Where to read more