From 55e0f36fb46cd3c5b54c4fb0d8444135c3dff0ac Mon Sep 17 00:00:00 2001
From: Dmitriy Vyukov <dvyukov@google.com>
Date: Tue, 15 Apr 2014 19:48:17 +0400
Subject: [PATCH] runtime: fix program termination when main goroutine calls
 Goexit Do not consider idle finalizer/bgsweep/timer goroutines as doing
 something useful. We can't simply set isbackground for the whole lifetime of
 the goroutines, because when finalizer goroutine calls user function, we do
 want to consider it as doing something useful. This is borken due to timers
 for quite some time. With background sweep is become even more broken. Fixes
 #7784.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/87960044
---
 src/pkg/runtime/crash_test.go | 28 ++++++++++++++++++++++++++++
 src/pkg/runtime/mgc0.c        |  4 ++++
 src/pkg/runtime/time.goc      |  2 ++
 3 files changed, 34 insertions(+)

diff --git a/src/pkg/runtime/crash_test.go b/src/pkg/runtime/crash_test.go
index 0e5056d822..cd9520b165 100644
--- a/src/pkg/runtime/crash_test.go
+++ b/src/pkg/runtime/crash_test.go
@@ -144,6 +144,15 @@ panic: again
 
 }
 
+func TestGoexitExit(t *testing.T) {
+	output := executeTest(t, goexitExitSource, nil)
+	want := ""
+	if output != want {
+		t.Fatalf("output:\n%s\n\nwanted:\n%s", output, want)
+	}
+
+}
+
 const crashSource = `
 package main
 
@@ -310,3 +319,22 @@ func main() {
 	panic("again")
 }
 `
+
+const goexitExitSource = `
+package main
+
+import (
+	"runtime"
+	"time"
+)
+
+func main() {
+	go func() {
+		time.Sleep(time.Millisecond)
+	}()
+	i := 0
+	runtime.SetFinalizer(&i, func(p *int) {})
+	runtime.GC()
+	runtime.Goexit()
+}
+`
diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index 26a18d36c7..be7f27e396 100644
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -1973,7 +1973,9 @@ bgsweep(void)
 			continue;
 		}
 		sweep.parked = true;
+		g->isbackground = true;
 		runtime·parkunlock(&gclock, "GC sweep wait");
+		g->isbackground = false;
 	}
 }
 
@@ -2618,7 +2620,9 @@ runfinq(void)
 		finq = nil;
 		if(fb == nil) {
 			runtime·fingwait = true;
+			g->isbackground = true;
 			runtime·parkunlock(&finlock, "finalizer wait");
+			g->isbackground = false;
 			continue;
 		}
 		runtime·unlock(&finlock);
diff --git a/src/pkg/runtime/time.goc b/src/pkg/runtime/time.goc
index d9393d7c8a..195c5c41a3 100644
--- a/src/pkg/runtime/time.goc
+++ b/src/pkg/runtime/time.goc
@@ -238,7 +238,9 @@ timerproc(void)
 		if(delta < 0) {
 			// No timers left - put goroutine to sleep.
 			timers.rescheduling = true;
+			g->isbackground = true;
 			runtime·parkunlock(&timers, "timer goroutine (idle)");
+			g->isbackground = false;
 			continue;
 		}
 		// At least one timer pending.  Sleep until then.
-- 
2.50.0