From fc12bb263683e43c0b93eb00071f894f5cfcc772 Mon Sep 17 00:00:00 2001 From: Alan Donovan Date: Thu, 30 Jun 2016 14:55:01 -0400 Subject: [PATCH] context: cancel the context in ExampleWithTimeout, with explanation Fixes #16230 Change-Id: Ibb10234a6c3ab8bd0cfd93c2ebe8cfa66f80f6b0 Reviewed-on: https://go-review.googlesource.com/24682 Reviewed-by: Brad Fitzpatrick --- src/context/withtimeout_test.go | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/context/withtimeout_test.go b/src/context/withtimeout_test.go index 2aea303bed..a3e8979c8c 100644 --- a/src/context/withtimeout_test.go +++ b/src/context/withtimeout_test.go @@ -13,13 +13,21 @@ import ( func ExampleWithTimeout() { // Pass a context with a timeout to tell a blocking function that it // should abandon its work after the timeout elapses. - ctx, _ := context.WithTimeout(context.Background(), 50*time.Millisecond) + ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond) + select { case <-time.After(1 * time.Second): fmt.Println("overslept") case <-ctx.Done(): fmt.Println(ctx.Err()) // prints "context deadline exceeded" } + + // Even though ctx should have expired already, it is good + // practice to call its cancelation function in any case. + // Failure to do so may keep the context and its parent alive + // longer than necessary. + cancel() + // Output: // context deadline exceeded } -- 2.50.0