Migrate to faster JSON library (#118)

Service log scraping is mainly spending time on marshalling and
unmarshalling log entries. Migration to json-iterator doubles the
performance.

Gopkg.toml

@@ -56,3 +56,7 @@
 [[constraint]]
   name = "github.com/allegro/go-metrics-graphite"
   revision = "d8aec135f2c1e2d0fd86f55e9b85427ba6592490"
+
+[[constraint]]
+  name = "github.com/json-iterator/go"
+  version = "1.1.3"

Makefile

@@ -43,7 +43,7 @@ package: $(BUILD_FOLDER)/executor
 	chmod 0755 $(BUILD_FOLDER)/executor-$(APPLICATION_VERSION)-linux-amd64.zip
 
 test: test-deps
-	go test -v -coverprofile=$(BUILD_FOLDER)/coverage.txt -covermode=atomic ./...
+	go test -coverprofile=$(BUILD_FOLDER)/coverage.txt -covermode=atomic ./...
 
 test-deps: $(BUILD_FOLDER)
 	./scripts/install-consul.sh

servicelog/appender/logstash.go

@@ -1,27 +1,29 @@
 package appender
 
 import (
-	"encoding/json"
 	"fmt"
 	"io"
 	"net"
 	"time"
 
-	"github.com/allegro/mesos-executor/xio"
-	"github.com/allegro/mesos-executor/xnet"
 	"github.com/hashicorp/consul/api"
+	"github.com/json-iterator/go"
 	"github.com/kelseyhightower/envconfig"
 	"github.com/rcrowley/go-metrics"
 	log "github.com/sirupsen/logrus"
 
 	"github.com/allegro/mesos-executor/servicelog"
+	"github.com/allegro/mesos-executor/xio"
+	"github.com/allegro/mesos-executor/xnet"
 )
 
 const (
 	logstashVersion      = 1
 	logstashConfigPrefix = "allegro_executor_servicelog_logstash"
 )
 
+var json = jsoniter.ConfigFastest
+
 type logstashConfig struct {
 	Protocol                 string `default:"tcp"`
 	Address                  string

servicelog/scraper/json.go

@@ -2,12 +2,12 @@ package scraper
 
 import (
 	"bufio"
-	"encoding/json"
 	"fmt"
 	"io"
 	"os"
 	"time"
 
+	"github.com/json-iterator/go"
 	log "github.com/sirupsen/logrus"
 
 	"github.com/allegro/mesos-executor/servicelog"
@@ -18,6 +18,8 @@ const (
 	megabyte = 1024 * kilobyte
 )
 
+var json = jsoniter.ConfigFastest
+
 // JSON is a scraper for logs represented as JSON objects.
 type JSON struct {
 	InvalidLogsWriter       io.Writer

servicelog/scraper/json_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"testing"
 	"time"
 
@@ -109,6 +110,25 @@ func TestIfIgnoresEmptyLogLines(t *testing.T) {
 	assert.NoError(t, err2)
 }
 
+func BenchmarkJSONScraping(b *testing.B) {
+	exampleLog, err := ioutil.ReadFile("testdata/log.json")
+	if err != nil {
+		b.Fatal(err)
+	}
+	reader, writer := io.Pipe()
+	scraper := JSON{}
+
+	entries := scraper.StartScraping(reader)
+	go func() {
+		for {
+			<-entries
+		}
+	}()
+	for i := 0; i < b.N; i++ {
+		writer.Write(exampleLog)
+	}
+}
+
 func noEntryWithTimeout(entries <-chan servicelog.Entry, timeout time.Duration) error {
 	timeoutChan := time.After(timeout)
 	select {

servicelog/scraper/testdata/log.json

@@ -0,0 +1 @@
+{"level": "INFO", "logger": "logger", "message": "In velit dolore duis dolor aute magna enim ex et excepteur et minim nostrud sint. Velit dolore deserunt Lorem eiusmod est elit nisi in. Sit tempor magna velit culpa eu proident. Ullamco eiusmod laborum eiusmod non laboris nostrud reprehenderit et officia in nulla cupidatat amet Lorem. Magna excepteur excepteur sint sint do aute. Qui eiusmod irure mollit consequat magna dolore minim nostrud exercitation. Proident officia amet dolor aliqua incididunt velit officia sit est aliquip officia."}