diff --git a/log/logger.go b/log/logger.go
index e4bcd954bc..9a253b424d 100644
--- a/log/logger.go
+++ b/log/logger.go
@@ -57,6 +57,8 @@ type Logger struct {
 	mutex        *sync.Mutex
 }
 
+var pid = os.Getpid()
+
 // NewLogger creates a new Logger.
 func NewLogger(name string, level int, target int) *Logger {
 	var logger Logger
@@ -190,7 +192,7 @@ func (logger *Logger) logf(format string, args ...interface{}) {
 	if logger.callCount%rotationCheckFrq == 0 {
 		logger.rotate()
 	}
-
+	format = fmt.Sprintf("[%v] %s", pid, format)
 	logger.callCount++
 	logger.l.Printf(format, args...)
 }
diff --git a/log/logger_test.go b/log/logger_test.go
index 10128ca91a..be753c3ecf 100644
--- a/log/logger_test.go
+++ b/log/logger_test.go
@@ -4,7 +4,10 @@
 package log
 
 import (
+	"fmt"
+	"io/ioutil"
 	"os"
+	"strings"
 	"testing"
 )
 
@@ -48,3 +51,26 @@ func TestLogFileRotatesWhenSizeLimitIsReached(t *testing.T) {
 	}
 	os.Remove(fn)
 }
+
+func TestPid(t *testing.T) {
+	l := NewLogger(logName, LevelInfo, TargetLogfile)
+	if l == nil {
+		t.Fatalf("Failed to create logger.")
+	}
+
+	l.Printf("LogText %v", 1)
+	l.Close()
+	fn := l.GetLogDirectory() + logName + ".log"
+	defer os.Remove(fn)
+	
+	logBytes, err := ioutil.ReadFile(fn)
+	if err != nil {
+		t.Fatalf("Failed to read log, %v", err)
+	}
+	log := string(logBytes)
+	exptectedLog := fmt.Sprintf("[%v] LogText 1", os.Getpid());
+
+	if  !strings.Contains(log, exptectedLog){
+		t.Fatalf("Unexpected log: %s.", log)
+	}
+}