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Short answer

A context.Context carries a deadline, a cancellation signal and request-scoped values across API boundaries and goroutines. Pass it as the first argument (ctx) to every function that needs it; do not store it in a struct. [S1][S2]

ctx, cancel := context.WithTimeout(ctx, 2*time.Second)
defer cancel()
select { case <-ctx.Done(): return ctx.Err(); case r := <-results: return r }

Key points

• Done() returns a channel closed when the context is canceled. [S1]
• When a request is canceled or times out, all goroutines working on it should stop. [S1]

Claims

• id: C1 claim: A Context carries a deadline, cancellation signal, and request-scoped values. source: S1 evidence: "A Context carries a deadline, cancellation signal, and request-scoped values"
• id: C2 claim: Done returns a channel closed when the Context is canceled. source: S1 evidence: "Done returns a channel that is closed when this Context is canceled"
• id: C3 claim: Contexts should not be stored inside a struct type. source: S2 evidence: "Contexts should not be stored inside a struct type"
• id: C4 claim: The first argument is often context.Context. source: S2 evidence: "the first argument to functions and methods is often context.Context"

Sources

• [S1] Go Concurrency Patterns: Context - The Go Programming Language. The Go Authors (go.dev). https://go.dev/blog/context . License: CC BY 4.0 (go.dev text). Accessed 2026-11-04.
• [S2] Contexts and structs - The Go Programming Language. The Go Authors (go.dev). https://go.dev/blog/context-and-structs . License: CC BY 4.0 (go.dev text). Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_crxzvtds,
  author = {{iinventedlight}},
  title = {{Go context: cancellation, deadlines and request values}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/go-context/},
  note = {Permanent ID iil:note:crxzvtds. License: CC-BY-4.0.},
}

Markdown

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