From 939dd5cb318f458175bb0b14ddcb82f6e244b52a Mon Sep 17 00:00:00 2001
From: Jakob Borg <jakob@nym.se>
Date: Tue, 12 Aug 2014 13:53:24 +0200
Subject: [PATCH] Add heap profiling support

---
 cmd/syncthing/heapprof.go  | 46 ++++++++++++++++++++++++++++++++++++++
 cmd/syncthing/perfstats.go |  4 ++++
 2 files changed, 50 insertions(+)
 create mode 100644 cmd/syncthing/heapprof.go

diff --git a/cmd/syncthing/heapprof.go b/cmd/syncthing/heapprof.go
new file mode 100644
index 000000000..6e6b17f13
--- /dev/null
+++ b/cmd/syncthing/heapprof.go
@@ -0,0 +1,46 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+// +build heapprof
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"syscall"
+	"time"
+)
+
+func init() {
+	go saveHeapProfiles()
+}
+
+func saveHeapProfiles() {
+	runtime.MemProfileRate = 1
+	var memstats, prevMemstats runtime.MemStats
+
+	t0 := time.Now()
+	for t := range time.NewTicker(250 * time.Millisecond).C {
+		startms := int(t.Sub(t0).Seconds() * 1000)
+		runtime.ReadMemStats(&memstats)
+		if memstats.HeapInuse > prevMemstats.HeapInuse {
+			fd, err := os.Create(fmt.Sprintf("heap-%05d-%07d.pprof", syscall.Getpid(), startms))
+			if err != nil {
+				panic(err)
+			}
+			err = pprof.WriteHeapProfile(fd)
+			if err != nil {
+				panic(err)
+			}
+			err = fd.Close()
+			if err != nil {
+				panic(err)
+			}
+			prevMemstats = memstats
+		}
+	}
+}
diff --git a/cmd/syncthing/perfstats.go b/cmd/syncthing/perfstats.go
index ffc78fa62..cb701a350 100644
--- a/cmd/syncthing/perfstats.go
+++ b/cmd/syncthing/perfstats.go
@@ -1,3 +1,7 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
 // +build perfstats
 
 package main