net: avoid darwin_arm64 bug in TestDialParallelSpuriousConnection

On darwin_arm64, reading from a socket at the same time as the other
end is closing it will occasionally hang for 60 seconds before
returning ECONNRESET. (This is a macOS issue, not a Go issue.)

Work around this condition by adding a brief sleep before the read.

Fixes #37795.

Change-Id: I63f92b91fb297cd66f89cdab707583afd50ab9c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/411155
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Damien Neil <dneil@google.com>

Author: neild

src/net/dial_test.go

@@ -405,6 +405,16 @@ func TestDialParallelSpuriousConnection(t *testing.T) {
 			t.Fatal(err)
 		}
 
+		// Workaround for https://go.dev/issue/37795.
+		// On arm64 macOS (current as of macOS 12.4),
+		// reading from a socket at the same time as the client
+		// is closing it occasionally hangs for 60 seconds before
+		// returning ECONNRESET. Sleep for a bit to give the
+		// socket time to close before trying to read from it.
+		if runtime.GOOS == "darwin" && runtime.GOARCH == "arm64" {
+			time.Sleep(10 * time.Millisecond)
+		}
+
 		// The client should close itself, without sending data.
 		c.SetReadDeadline(readDeadline)
 		var b [1]byte