Added benchmark test to test json serialization. Made sure http client would reuse connection.

plugins/outputs/opentsdb/opentsdb_http.go

@@ -3,9 +3,8 @@ package opentsdb
 import (
     "fmt"
     "encoding/json"
-	//"os"
 	"io"
-	//"io/ioutil"
+	"io/ioutil"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
@@ -91,15 +90,9 @@ func (r *requestBody) close() error {
     return nil
 }
 
-func (o *openTSDBHttp) startNewRequest() error {
-    o.body.reset(o.Debug)
-
-    return nil
-}
-
 func (o *openTSDBHttp) sendDataPoint(metric *HttpMetric) error {
     if o.metricCounter == 0 {
-        o.startNewRequest()
+        o.body.reset(o.Debug)
     }
 
     if err := o.body.addMetric(metric); err != nil {
@@ -139,7 +132,7 @@ func (o *openTSDBHttp) flush() error {
 	if err != nil {
 		return fmt.Errorf("Error when building request: %s", err.Error())
 	}
-	req.Header.Add("Content-Type", "applicaton/json")
+	req.Header.Set("Content-Type", "applicaton/json")
 	req.Header.Set("Content-Encoding", "gzip")
 
 	if (o.Debug) {
@@ -165,6 +158,9 @@ func (o *openTSDBHttp) flush() error {
 	    }
 
 		fmt.Printf("Received response\n%s\n\n", dump)
+	} else {
+        // Important so http client reuse connection for next request if need be.
+        io.Copy(ioutil.Discard, resp.Body)
     }
 
 	if resp.StatusCode/100 != 2 {

plugins/outputs/opentsdb/opentsdb_test.go

@@ -3,8 +3,16 @@ package opentsdb
 import (
 	"reflect"
 	"testing"
-	// "github.com/influxdata/telegraf/testutil"
+	"fmt"
-	// "github.com/stretchr/testify/require"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strconv"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/testutil"
+	//"github.com/stretchr/testify/require"
 )
 
 func TestCleanTags(t *testing.T) {
@@ -67,6 +75,47 @@ func TestBuildTagsTelnet(t *testing.T) {
 	}
 }
 
+func BenchmarkHttpSend(b *testing.B) {
+	const BatchSize = 50
+	const MetricsCount = 4*BatchSize
+	metrics := make([]telegraf.Metric, MetricsCount)
+	for i:=0; i<MetricsCount; i++ {
+		metrics[i] = testutil.TestMetric(1.0)
+	}
+
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+        w.Header().Set("Content-Type", "application/json")
+        fmt.Fprintln(w, "{}")
+    }))
+    defer ts.Close()
+
+	u, err := url.Parse(ts.URL)
+	if err != nil {
+		panic(err)
+	}
+
+	host, p, _ := net.SplitHostPort(u.Host)
+
+	port, err := strconv.Atoi(p)
+	if err != nil {
+		panic(err)
+	}
+
+	o := &OpenTSDB{
+	 		Host:   host,
+	 		Port:   port,
+	 		Prefix: "",
+			UseHttp: true,
+			BatchSize: BatchSize,
+	 }
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		o.Write(metrics)
+    }
+}
+
 // func TestWrite(t *testing.T) {
 // 	if testing.Short() {
 // 		t.Skip("Skipping integration test in short mode")