runtime: delay exiting while panic is running deferred functions

Try to avoid a race between the main goroutine exiting and a panic
occurring. Don't try too hard, to avoid hanging.

Updates #3934
Fixes #20018

Change-Id: I57a02b6d795d2a61f1cadd137ce097145280ece7
Reviewed-on: https://go-review.googlesource.com/41052
Reviewed-by: Austin Clements <austin@google.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/src/runtime/testdata/testprog/panicrace.go b/src/runtime/testdata/testprog/panicrace.go
new file mode 100644
index 0000000000..f0589940b5
--- /dev/null
+++ b/src/runtime/testdata/testprog/panicrace.go
@@ -0,0 +1,27 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"runtime"
+	"sync"
+)
+
+func init() {
+	register("PanicRace", PanicRace)
+}
+
+func PanicRace() {
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer func() {
+			wg.Done()
+			runtime.Gosched()
+		}()
+		panic("crash")
+	}()
+	wg.Wait()
+}