diff --git a/go/master/c/client.go b/go/master/c/client.go
new file mode 100644
index 0000000000000000000000000000000000000000..220184c3af73118a8dc6488370ebf9ea4d8d6137
--- /dev/null
+++ b/go/master/c/client.go
@@ -0,0 +1,81 @@
+package main
+
+/*
+
+typedef int paddle_master_client;
+*/
+import "C"
+
+import (
+	"log"
+	"sync"
+	"unsafe"
+
+	"github.com/PaddlePaddle/Paddle/go/master"
+)
+
+var mu sync.Mutex
+var handleMap = make(map[C.paddle_master_client]*master.Client)
+var curHandle C.paddle_master_client
+
+func add(c *master.Client) C.paddle_master_client {
+	mu.Lock()
+	defer mu.Unlock()
+	client := curHandle
+	curHandle++
+	handleMap[client] = c
+	return client
+}
+
+func get(client C.paddle_master_client) *master.Client {
+	mu.Lock()
+	defer mu.Unlock()
+	return handleMap[client]
+}
+
+func remove(client C.paddle_master_client) *master.Client {
+	mu.Lock()
+	defer mu.Unlock()
+	h := handleMap[client]
+	delete(handleMap, client)
+	return h
+}
+
+type addresser string
+
+func (a addresser) Address() string {
+	return string(a)
+}
+
+//paddle_new_master_client
+func paddle_new_master_client(addr *C.char, buf_size C.int) C.paddle_master_client {
+	a := C.GoString(addr)
+	c := master.NewClient(addresser(a), int(buf_size))
+	return add(c)
+}
+
+//export paddle_new_etcd_master_client
+func paddle_new_etcd_master_client(etcd_addr *C.char) C.paddle_master_client {
+	// TODO(helin): fault tolerant master client using etcd.
+	panic("not implemented.")
+}
+
+//export paddle_set_dataset
+func paddle_set_dataset(client C.paddle_master_client, path **C.char, size C.int) C.int {
+	c := get(client)
+	var paths []string
+	for i := 0; i < int(size); i++ {
+		ptr := (**C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(path)) + uintptr(size)))
+		str := C.GoString(*ptr)
+		paths = append(paths, str)
+	}
+	err := c.SetDataset(paths)
+	if err != nil {
+		log.Println(err)
+		return -1
+	}
+
+	return 0
+}
+
+func main() {}
diff --git a/go/master/client.go b/go/master/client.go
index 20c66340dc28bc514b6c51583dd94830c42a41bf..1c8a8d73d0ca755f6ce13d0e2cc494a3443e3c50 100644
--- a/go/master/client.go
+++ b/go/master/client.go
@@ -2,9 +2,11 @@ package master
 
 import (
 	"log"
+	"os"
 	"time"
 
 	"github.com/PaddlePaddle/Paddle/go/connection"
+	"github.com/PaddlePaddle/recordio"
 )
 
 // Addresser provide the address of the master server.
@@ -15,16 +17,51 @@ type Addresser interface {
 // Client is the client of the master server.
 type Client struct {
 	conn *connection.Conn
+	ch   chan []byte
 }
 
 // NewClient creates a new Client.
-func NewClient(addr Addresser) *Client {
+//
+// bufSize is the record buffer size. NextRecord will read from the
+// buffer.
+func NewClient(addr Addresser, bufSize int) *Client {
 	c := &Client{}
 	c.conn = connection.New()
+	c.ch = make(chan []byte, bufSize)
 	go c.monitorMaster(addr)
+	go c.getRecords()
 	return c
 }
 
+func (c *Client) getRecords() {
+	for {
+		t, err := c.getTask()
+		if err != nil {
+			log.Println(err)
+			continue
+		}
+
+		for _, chunk := range t.Chunks {
+			f, err := os.Open(chunk.Path)
+			if err != nil {
+				log.Println(err)
+				continue
+			}
+
+			s := recordio.NewRangeScanner(f, &chunk.Index, -1, -1)
+			for s.Scan() {
+				c.ch <- s.Record()
+			}
+
+			err = f.Close()
+			if err != nil {
+				log.Println(err)
+			}
+		}
+		c.taskFinished(t.ID)
+	}
+}
+
 func (c *Client) monitorMaster(addr Addresser) {
 	lastMaster := ""
 	monitor := func() {
@@ -69,14 +106,22 @@ func (c *Client) SetDataset(globPaths []string) error {
 	return c.conn.Call("Service.SetDataset", globPaths, nil)
 }
 
-// GetTask gets a new task from the master server.
-func (c *Client) GetTask() (Task, error) {
+// getTask gets a new task from the master server.
+func (c *Client) getTask() (Task, error) {
 	var t Task
 	err := c.conn.Call("Service.GetTask", 0, &t)
 	return t, err
 }
 
 // TaskFinished tells the master server a task is finished.
-func (c *Client) TaskFinished(taskID int) error {
+func (c *Client) taskFinished(taskID int) error {
 	return c.conn.Call("Service.TaskFinished", taskID, nil)
 }
+
+// NextRecord returns next record in the dataset.
+//
+// NextRecord will block until next record is available. It is
+// thread-safe.
+func (c *Client) NextRecord() []byte {
+	return <-c.ch
+}
diff --git a/go/master/client_internal_test.go b/go/master/client_internal_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..362668202a7eb3f7f04a9d93c3e8eeb9a63c2619
--- /dev/null
+++ b/go/master/client_internal_test.go
@@ -0,0 +1,120 @@
+package master
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+	"net/rpc"
+	"os"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/PaddlePaddle/Paddle/go/connection"
+	"github.com/PaddlePaddle/recordio"
+)
+
+const (
+	totalTask    = 20
+	chunkPerTask = 10
+)
+
+func init() {
+	log.SetLevel(log.ErrorLevel)
+}
+
+type TestAddresser string
+
+func (a TestAddresser) Address() string {
+	return string(a)
+}
+
+func TestGetFinishTask(t *testing.T) {
+	const path = "/tmp/master_client_test_0"
+
+	l, err := net.Listen("tcp", ":0")
+	if err != nil {
+		panic(err)
+	}
+
+	ss := strings.Split(l.Addr().String(), ":")
+	p, err := strconv.Atoi(ss[len(ss)-1])
+	if err != nil {
+		panic(err)
+	}
+
+	go func(l net.Listener) {
+		s := NewService(chunkPerTask, time.Second, 1)
+		server := rpc.NewServer()
+		err := server.Register(s)
+		if err != nil {
+			panic(err)
+		}
+
+		mux := http.NewServeMux()
+		mux.Handle(rpc.DefaultRPCPath, server)
+		err = http.Serve(l, mux)
+		if err != nil {
+			panic(err)
+		}
+	}(l)
+
+	f, err := os.Create(path)
+	if err != nil {
+		panic(err)
+	}
+
+	for i := 0; i < totalTask*chunkPerTask; i++ {
+		w := recordio.NewWriter(f, -1, -1)
+		w.Write(nil)
+		// call Close to force RecordIO writing a chunk.
+		w.Close()
+	}
+	f.Close()
+
+	c := &Client{}
+	c.conn = connection.New()
+	go c.monitorMaster(TestAddresser(fmt.Sprintf(":%d", p)))
+	c.SetDataset([]string{path})
+
+	checkOnePass := func(i int) {
+		var tasks []Task
+		for idx := 0; idx < totalTask; idx++ {
+			task, err := c.getTask()
+			if err != nil {
+				t.Fatal(err, " pass:", i)
+			}
+			tasks = append(tasks, task)
+		}
+
+		_, err = c.getTask()
+		if err == nil {
+			t.Fatal("Should get error. Pass:", i)
+		}
+
+		err = c.taskFinished(tasks[0].ID)
+		if err != nil {
+			t.Fatal(err, "pass:", i)
+		}
+		tasks = tasks[1:]
+		task, err := c.getTask()
+		if err != nil {
+			t.Fatal(err)
+		}
+		tasks = append(tasks, task)
+
+		for _, task := range tasks {
+			err = c.taskFinished(task.ID)
+			if err != nil {
+				t.Fatal(err, " pass:", i)
+			}
+		}
+	}
+
+	for i := 0; i < 10; i++ {
+		checkOnePass(i)
+	}
+}
diff --git a/go/master/client_test.go b/go/master/client_test.go
index df708ad7912c07205ae0cee8d2ab1c06d65223cc..2b3f873ecf3a650cd91d1d9c20b414b05bbb0cd6 100644
--- a/go/master/client_test.go
+++ b/go/master/client_test.go
@@ -11,21 +11,15 @@ import (
 	"testing"
 	"time"
 
-	log "github.com/sirupsen/logrus"
-
 	"github.com/PaddlePaddle/Paddle/go/master"
 	"github.com/PaddlePaddle/recordio"
 )
 
-const (
-	totalTask    = 20
-	chunkPerTask = 10
-)
-
-var port int
-
-func init() {
-	log.SetLevel(log.ErrorLevel)
+func TestNextRecord(t *testing.T) {
+	const (
+		path  = "/tmp/master_client_TestFull"
+		total = 50
+	)
 
 	l, err := net.Listen("tcp", ":0")
 	if err != nil {
@@ -37,10 +31,9 @@ func init() {
 	if err != nil {
 		panic(err)
 	}
-	port = p
 
 	go func(l net.Listener) {
-		s := master.NewService(chunkPerTask, time.Second, 1)
+		s := master.NewService(10, time.Second, 1)
 		server := rpc.NewServer()
 		err := server.Register(s)
 		if err != nil {
@@ -54,67 +47,33 @@ func init() {
 			panic(err)
 		}
 	}(l)
-}
 
-type addresser string
-
-func (a addresser) Address() string {
-	return string(a)
-}
-
-func TestClientFull(t *testing.T) {
-	const p = "/tmp/master_client_test_0"
-	f, err := os.Create(p)
+	f, err := os.Create(path)
 	if err != nil {
 		panic(err)
 	}
 
-	for i := 0; i < totalTask*chunkPerTask; i++ {
-		w := recordio.NewWriter(f, -1, -1)
-		w.Write(nil)
-		// call Close to force RecordIO writing a chunk.
-		w.Close()
+	w := recordio.NewWriter(f, -1, -1)
+	for i := 0; i < total; i++ {
+		w.Write([]byte{byte(i)})
 	}
+	w.Close()
 	f.Close()
 
-	c := master.NewClient(addresser(fmt.Sprintf(":%d", port)))
-	c.SetDataset([]string{p})
+	c := master.NewClient(master.TestAddresser(fmt.Sprintf(":%d", p)), 10)
+	c.SetDataset([]string{path})
 
-	checkOnePass := func(i int) {
-		var tasks []master.Task
-		for i := 0; i < totalTask; i++ {
-			task, err := c.GetTask()
-			if err != nil {
-				t.Fatal(i, err)
+	for pass := 0; pass < 50; pass++ {
+		received := make(map[byte]bool)
+		for i := 0; i < total; i++ {
+			r := c.NextRecord()
+			if len(r) != 1 {
+				t.Fatal("Length should be 1.", r)
 			}
-			tasks = append(tasks, task)
-		}
-
-		_, err = c.GetTask()
-		if err == nil {
-			t.Fatal(i, "should get error.")
-		}
-
-		err = c.TaskFinished(tasks[0].ID)
-		if err != nil {
-			t.Fatal(err)
-		}
-		tasks = tasks[1:]
-		task, err := c.GetTask()
-		if err != nil {
-			t.Fatal(err)
-		}
-		tasks = append(tasks, task)
-
-		for _, task := range tasks {
-			err = c.TaskFinished(task.ID)
-			if err != nil {
-				t.Fatal(i, err)
+			if received[r[0]] {
+				t.Fatal("Received duplicate.", received, r)
 			}
+			received[r[0]] = true
 		}
 	}
-
-	for i := 0; i < 10; i++ {
-		checkOnePass(i)
-	}
 }
diff --git a/go/master/service.go b/go/master/service.go
index 1e2a34972bb4763688d7df97d768320cd6f9e9d4..2e165138fb896ab5e43ec792e0b8110aa4834e85 100644
--- a/go/master/service.go
+++ b/go/master/service.go
@@ -217,6 +217,16 @@ func (s *Service) checkTimeoutFunc(taskID int, epoch int) func() {
 	}
 }
 
+// must be called with lock held.
+func (s *Service) logFields() log.Fields {
+	return log.Fields{
+		"todoLen":    len(s.taskQueues.Todo),
+		"pendingLen": len(s.taskQueues.Pending),
+		"doneLen":    len(s.taskQueues.Done),
+		"failedLen":  len(s.taskQueues.Failed),
+	}
+}
+
 // GetTask gets a new task from the service.
 func (s *Service) GetTask(dummy int, task *Task) error {
 	select {
@@ -230,7 +240,7 @@ func (s *Service) GetTask(dummy int, task *Task) error {
 		if len(s.taskQueues.Done) == 0 {
 			if len(s.taskQueues.Pending) == 0 {
 				err := errors.New("all task failed")
-				log.Warningln(err)
+				log.WithFields(s.logFields()).Warningln("All tasks failed.")
 				return err
 			}
 
@@ -243,12 +253,12 @@ func (s *Service) GetTask(dummy int, task *Task) error {
 			// in package. So we need to figure out a way
 			// for client to check this error correctly.
 			err := errors.New("no more available task")
-			log.Warningln(err)
+			log.WithFields(s.logFields()).Warningln("No more available task.")
 			return err
 		}
 		s.taskQueues.Todo = s.taskQueues.Done
 		s.taskQueues.Done = nil
-		log.Infoln("No more todo task, but trainer is requesting task to do. Move all done task to todo.")
+		log.WithFields(s.logFields()).Infoln("No more todo task, but trainer is requesting task to do. Move all done task to todo.")
 	}
 
 	t := s.taskQueues.Todo[0]
@@ -261,7 +271,7 @@ func (s *Service) GetTask(dummy int, task *Task) error {
 	}
 
 	*task = t.Task
-	log.Infof("Task #%d dispatched\n", task.ID)
+	log.WithFields(s.logFields()).Infof("Task #%d dispatched.", task.ID)
 
 	time.AfterFunc(s.timeoutDur, s.checkTimeoutFunc(t.Task.ID, t.Epoch))
 	return nil
@@ -276,12 +286,10 @@ func (s *Service) TaskFinished(taskID int, dummy *int) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	log.Infof("Task %d finished\n", taskID)
-
 	t, ok := s.taskQueues.Pending[taskID]
 	if !ok {
 		err := errors.New("pending task not found")
-		log.Warningln(err)
+		log.WithFields(s.logFields()).Warningln("Pending task #%d not found.", taskID)
 		return err
 	}
 
@@ -290,8 +298,10 @@ func (s *Service) TaskFinished(taskID int, dummy *int) error {
 	s.taskQueues.Done = append(s.taskQueues.Done, t)
 	delete(s.taskQueues.Pending, taskID)
 
+	log.WithFields(s.logFields()).Infof("Task #%d finished.", taskID)
+
 	if len(s.taskQueues.Pending) == 0 && len(s.taskQueues.Todo) == 0 {
-		log.Infoln("No more todo and pending task, start a new pass.")
+		log.WithFields(s.logFields()).Infoln("No more todo and pending task, start a new pass.")
 		s.taskQueues.Todo = append(s.taskQueues.Todo, s.taskQueues.Done...)
 		s.taskQueues.Done = nil
 	}