context: mention asynchronous cancellation propagation

Fixes #33185

Change-Id: I0adcffa5d1c9e55ae52309c59f961b0710166098
Reviewed-on: https://go-review.googlesource.com/c/go/+/187921
Reviewed-by: Sameer Ajmani <sameer@golang.org>
Run-TryBot: Sameer Ajmani <sameer@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/context/context.go b/src/context/context.go
index 62590850a66220027342acbfdcd64218aa11f6b8..390f93c078f2dae96008f2745fb39153be7c50a8 100644 (file)
--- a/src/context/context.go
+++ b/src/context/context.go
@@ -67,6 +67,8 @@ type Context interface {
        // Done returns a channel that's closed when work done on behalf of this
        // context should be canceled. Done may return nil if this context can
        // never be canceled. Successive calls to Done return the same value.
+       // The close of the Done channel may happen asynchronously,
+       // after the cancel function returns.
        //
        // WithCancel arranges for Done to be closed when cancel is called;
        // WithDeadline arranges for Done to be closed when the deadline