From 57933b86b1a09a44d1350437f42a3305a30ad2b3 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Tue, 30 Jul 2013 22:52:10 -0400
Subject: [PATCH] cmd/go: send timed out test SIGQUIT before SIGKILL

There is a chance that the SIGQUIT will make the test process
dump its stacks as part of exiting, which would be nice for
finding out what it is doing.

Right now the builders are occasionally timing out running
the runtime test. I hope this will give us some information
about the state of the runtime.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/12041051
---
 src/cmd/go/signal_notunix.go |  4 ++++
 src/cmd/go/signal_unix.go    |  4 ++++
 src/cmd/go/test.go           | 13 +++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/src/cmd/go/signal_notunix.go b/src/cmd/go/signal_notunix.go
index ef13c19195..29aa9d8c20 100644
--- a/src/cmd/go/signal_notunix.go
+++ b/src/cmd/go/signal_notunix.go
@@ -11,3 +11,7 @@ import (
 )
 
 var signalsToIgnore = []os.Signal{os.Interrupt}
+
+// signalTrace is the signal to send to make a Go program
+// crash with a stack trace.
+var signalTrace os.Signal = nil
diff --git a/src/cmd/go/signal_unix.go b/src/cmd/go/signal_unix.go
index 489a73b83b..124f356bf8 100644
--- a/src/cmd/go/signal_unix.go
+++ b/src/cmd/go/signal_unix.go
@@ -12,3 +12,7 @@ import (
 )
 
 var signalsToIgnore = []os.Signal{os.Interrupt, syscall.SIGQUIT}
+
+// signalTrace is the signal to send to make a Go program
+// crash with a stack trace.
+var signalTrace os.Signal = syscall.SIGQUIT
diff --git a/src/cmd/go/test.go b/src/cmd/go/test.go
index e51b5a45d1..c197007c43 100644
--- a/src/cmd/go/test.go
+++ b/src/cmd/go/test.go
@@ -896,10 +896,23 @@ func (b *builder) runTest(a *action) error {
 		go func() {
 			done <- cmd.Wait()
 		}()
+	Outer:
 		select {
 		case err = <-done:
 			// ok
 		case <-tick.C:
+			if signalTrace != nil {
+				// Send a quit signal in the hope that the program will print
+				// a stack trace and exit. Give it five seconds before resorting
+				// to Kill.
+				cmd.Process.Signal(signalTrace)
+				select {
+				case err = <-done:
+					fmt.Fprintf(&buf, "*** Test killed with %v: ran too long (%v).\n", signalTrace, testKillTimeout)
+					break Outer
+				case <-time.After(5 * time.Second):
+				}
+			}
 			cmd.Process.Kill()
 			err = <-done
 			fmt.Fprintf(&buf, "*** Test killed: ran too long (%v).\n", testKillTimeout)