trace: initialize templates lazily
Parsing the templates can take a significant amount of
time(30-35ms) so it should not be done on the init phase.
Change-Id: I8f258b8028510e698a97b55faeac0d28a61b7b22
Reviewed-on: https://go-review.googlesource.com/21654
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/trace/events.go b/trace/events.go
index e66c7e3..d8daec1 100644
--- a/trace/events.go
+++ b/trace/events.go
@@ -21,11 +21,6 @@
"time"
)
-var eventsTmpl = template.Must(template.New("events").Funcs(template.FuncMap{
- "elapsed": elapsed,
- "trimSpace": strings.TrimSpace,
-}).Parse(eventsHTML))
-
const maxEventsPerLog = 100
type bucket struct {
@@ -101,7 +96,7 @@
famMu.RLock()
defer famMu.RUnlock()
- if err := eventsTmpl.Execute(w, data); err != nil {
+ if err := eventsTmpl().Execute(w, data); err != nil {
log.Printf("net/trace: Failed executing template: %v", err)
}
}
@@ -421,6 +416,19 @@
}
}
+var eventsTmplCache *template.Template
+var eventsTmplOnce sync.Once
+
+func eventsTmpl() *template.Template {
+ eventsTmplOnce.Do(func() {
+ eventsTmplCache = template.Must(template.New("events").Funcs(template.FuncMap{
+ "elapsed": elapsed,
+ "trimSpace": strings.TrimSpace,
+ }).Parse(eventsHTML))
+ })
+ return eventsTmplCache
+}
+
const eventsHTML = `
<html>
<head>
diff --git a/trace/histogram.go b/trace/histogram.go
index bb42aa5..9bf4286 100644
--- a/trace/histogram.go
+++ b/trace/histogram.go
@@ -12,6 +12,7 @@
"html/template"
"log"
"math"
+ "sync"
"golang.org/x/net/internal/timeseries"
)
@@ -320,15 +321,20 @@
func (h *histogram) html() template.HTML {
buf := new(bytes.Buffer)
- if err := distTmpl.Execute(buf, h.newData()); err != nil {
+ if err := distTmpl().Execute(buf, h.newData()); err != nil {
buf.Reset()
log.Printf("net/trace: couldn't execute template: %v", err)
}
return template.HTML(buf.String())
}
-// Input: data
-var distTmpl = template.Must(template.New("distTmpl").Parse(`
+var distTmplCache *template.Template
+var distTmplOnce sync.Once
+
+func distTmpl() *template.Template {
+ distTmplOnce.Do(func() {
+ // Input: data
+ distTmplCache = template.Must(template.New("distTmpl").Parse(`
<table>
<tr>
<td style="padding:0.25em">Count: {{.Count}}</td>
@@ -354,3 +360,6 @@
{{end}}
</table>
`))
+ })
+ return distTmplCache
+}
diff --git a/trace/trace.go b/trace/trace.go
index ecd766e..64f56a3 100644
--- a/trace/trace.go
+++ b/trace/trace.go
@@ -238,7 +238,7 @@
completedMu.RLock()
defer completedMu.RUnlock()
- if err := pageTmpl.ExecuteTemplate(w, "Page", data); err != nil {
+ if err := pageTmpl().ExecuteTemplate(w, "Page", data); err != nil {
log.Printf("net/trace: Failed executing template: %v", err)
}
}
@@ -902,10 +902,18 @@
return string(b)
}
-var pageTmpl = template.Must(template.New("Page").Funcs(template.FuncMap{
- "elapsed": elapsed,
- "add": func(a, b int) int { return a + b },
-}).Parse(pageHTML))
+var pageTmplCache *template.Template
+var pageTmplOnce sync.Once
+
+func pageTmpl() *template.Template {
+ pageTmplOnce.Do(func() {
+ pageTmplCache = template.Must(template.New("Page").Funcs(template.FuncMap{
+ "elapsed": elapsed,
+ "add": func(a, b int) int { return a + b },
+ }).Parse(pageHTML))
+ })
+ return pageTmplCache
+}
const pageHTML = `
{{template "Prolog" .}}
diff --git a/trace/trace_test.go b/trace/trace_test.go
index c6aad86..bfd9dfe 100644
--- a/trace/trace_test.go
+++ b/trace/trace_test.go
@@ -70,6 +70,20 @@
}
}
+// TestParseTemplate checks that all templates used by this package are valid
+// as they are parsed on first usage
+func TestParseTemplate(t *testing.T) {
+ if tmpl := distTmpl(); tmpl == nil {
+ t.Error("invalid template returned from distTmpl()")
+ }
+ if tmpl := pageTmpl(); tmpl == nil {
+ t.Error("invalid template returned from pageTmpl()")
+ }
+ if tmpl := eventsTmpl(); tmpl == nil {
+ t.Error("invalid template returned from eventsTmpl()")
+ }
+}
+
func benchmarkTrace(b *testing.B, maxEvents, numEvents int) {
numSpans := (b.N + numEvents + 1) / numEvents
