Pserver etcd registration

go/cmd/pserver/pserver.go

@@ -5,18 +5,35 @@ import (
 	"net/http"
 	"net/rpc"
 	"strconv"
+	"time"
 
 	"github.com/namsral/flag"
 
 	"github.com/PaddlePaddle/Paddle/go/pserver"
+	log "github.com/sirupsen/logrus"
 )
 
 func main() {
 	port := flag.Int("port", 0, "port of the pserver")
+	etcdEndpoint := flag.String("etcd-endpoint", "http://127.0.0.1:2379",
+		"comma separated endpoint string for pserver to connect to etcd")
+	etcdTimeout := flag.Int("etcd-timeout", 5, "timeout for etcd calls")
+	logLevel := flag.String("log-level", "info",
+		"log level, possible values: debug, info, warning, error, fatal, panic")
 	flag.Parse()
 
-	s := pserver.NewService()
-	err := rpc.Register(s)
+	level, err := log.ParseLevel(*logLevel)
+	if err != nil {
+		panic(err)
+	}
+	log.SetLevel(level)
+
+	timeout := time.Second * time.Duration((*etcdTimeout))
+	s, err := pserver.NewService(*etcdEndpoint, timeout)
+	if err != nil {
+		panic(err)
+	}
+	err = rpc.Register(s)
 	if err != nil {
 		panic(err)
 	}
@@ -27,7 +44,9 @@ func main() {
 		panic(err)
 	}
 
+	log.Infof("start pserver at port %d", *port)
 	err = http.Serve(l, nil)
+
 	if err != nil {
 		panic(err)
 	}

go/pserver/client_test.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/PaddlePaddle/Paddle/go/pserver"
 )
@@ -30,9 +31,12 @@ func init() {
 		port[i] = p
 
 		go func(l net.Listener) {
-			s := pserver.NewService()
+			s, err := pserver.NewService("", time.Second*5)
+			if err != nil {
+				panic(err)
+			}
 			server := rpc.NewServer()
-			err := server.Register(s)
+			err = server.Register(s)
 			if err != nil {
 				panic(err)
 			}

go/pserver/service.go

@@ -1,9 +1,18 @@
 package pserver
 
 import (
+	"context"
 	"errors"
 	"fmt"
+	"strconv"
+	"strings"
 	"sync"
+	"time"
+
+	"github.com/PaddlePaddle/Paddle/go/utils/networkhelper"
+	"github.com/coreos/etcd/clientv3"
+	"github.com/coreos/etcd/clientv3/concurrency"
+	log "github.com/sirupsen/logrus"
 )
 
 // ElementType is the type of elements of a Parameter.
@@ -24,6 +33,9 @@ const (
 	Float64
 )
 
+// PsDesired is etcd path for store desired pserver count
+const PsDesired = "/ps_desired"
+
 // Parameter is a piece of data to sync with the parameter server.
 type Parameter struct {
 	Name        string
@@ -47,14 +59,121 @@ type Service struct {
 	mu       sync.Mutex
 	opt      *optimizer
 	paramMap map[string]Parameter
+
+	etcdEndpoints string
+	etcdClient    *clientv3.Client
+	// etcdTimeout is also used as retry intervals.
+	etcdTimeout time.Duration
+	// desired number of pservers in the job.
+	// assume desired will not change during one training job.
+	desired int
+	// FIXME: ensure GetExternalIP gets the correct ip for trainers to connect.
+	externalIP string
 }
 
-// NewService creates a new service.
-func NewService() *Service {
+// NewService creates a new service, will bypass etcd registration if no
+// endpoints specified.
+func NewService(endpoints string, timeout time.Duration) (*Service, error) {
 	s := &Service{opt: newOptimizer(sgd, 0.005)}
 	s.paramMap = make(map[string]Parameter)
 	s.initialized = make(chan struct{})
-	return s
+	s.etcdEndpoints = endpoints
+	s.etcdTimeout = timeout
+
+	var err error
+	s.externalIP, err = networkhelper.GetExternalIP()
+	if err != nil {
+		return nil, err
+	}
+
+	if endpoints != "" {
+		// initialize connection to etcd, try
+		ep := strings.Split(s.etcdEndpoints, ",")
+		for {
+			cli, err := clientv3.New(clientv3.Config{
+				Endpoints:   ep,
+				DialTimeout: s.etcdTimeout,
+			})
+			if err != nil {
+				log.Errorf("connect to etcd error: %v", err)
+				time.Sleep(s.etcdTimeout)
+				continue
+			}
+			s.etcdClient = cli
+			log.Debugf("inited client to %s", s.etcdEndpoints)
+			break
+		}
+		// wait and set s.desired init value
+		for {
+			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+			resp, err := s.etcdClient.Get(ctx, PsDesired)
+			cancel()
+			if err != nil {
+				log.Errorf("getting %s error: %v", PsDesired, err)
+				time.Sleep(s.etcdTimeout)
+				continue
+			}
+			if len(resp.Kvs) != 0 {
+				s.desired, err = strconv.Atoi(string(resp.Kvs[0].Value))
+				if err != nil {
+					log.Errorf("value of %s invalid %v\n", PsDesired, err)
+					time.Sleep(s.etcdTimeout)
+					// NOTE: wait util ps_desired value change
+					continue
+				}
+				break
+			}
+		}
+		// try register pserver node on etcd
+		for {
+			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+			_, err := s.registerPserverEtcd(ctx)
+			cancel()
+			if err != nil {
+				log.Warn(err)
+				time.Sleep(s.etcdTimeout)
+				continue
+			}
+			break
+		}
+	} // if endpoints != ""
+	// Bypass etcd registration if no endpoints specified
+	return s, nil
+}
+
+// registerPserverEtcd registers pserver node on etcd using transaction.
+func (s *Service) registerPserverEtcd(ctx context.Context) (*clientv3.TxnResponse, error) {
+	return concurrency.NewSTM(s.etcdClient, func(c concurrency.STM) error {
+		registered := false
+		for i := 0; i < s.desired; i++ {
+			psKey := "/ps/" + strconv.Itoa(i)
+			log.Debugf("checking %s", psKey)
+			ps := c.Get(psKey)
+			log.Debugf("got value (%s) for key: %s", ps, psKey)
+
+			if ps == "" {
+				resp, err := s.etcdClient.Grant(context.TODO(), 5)
+				if err != nil {
+					log.Fatal(err)
+				}
+				// find the first id and write info
+				c.Put(psKey, s.externalIP, clientv3.WithLease(resp.ID))
+				log.Debugf("set pserver node %s with value %s", psKey, s.externalIP)
+				_, kaerr := s.etcdClient.KeepAlive(context.TODO(), resp.ID)
+				if kaerr != nil {
+					log.Errorf("keepalive etcd node error: %v", kaerr)
+					return kaerr
+				}
+				log.Debug("register finished")
+				registered = true
+				break
+			}
+		}
+		if registered == true {
+			return nil
+		}
+		return errors.New("not registerd, may due to already have enough pservers")
+	}, concurrency.WithAbortContext(ctx), concurrency.WithIsolation(concurrency.RepeatableReads))
 }
 
 // InitParam initializes a parameter.

go/pserver/service_test.go

@@ -10,12 +10,15 @@ import (
 )
 
 func TestFull(t *testing.T) {
-	s := pserver.NewService()
+	s, err := pserver.NewService("", time.Second*5)
+	if err != nil {
+		t.Error(err)
+	}
 	var p pserver.Parameter
 	p.Name = "param_a"
 	p.Content = []byte{1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0}
 	p.ElementType = pserver.Int32
-	err := s.InitParam(pserver.ParameterWithConfig{Param: p, Config: nil}, nil)
+	err = s.InitParam(pserver.ParameterWithConfig{Param: p, Config: nil}, nil)
 	if err != nil {
 		t.FailNow()
 	}
@@ -72,8 +75,11 @@ func TestFull(t *testing.T) {
 }
 
 func TestMultipleInit(t *testing.T) {
-	s := pserver.NewService()
-	err := s.FinishInitParams(0, nil)
+	s, err := pserver.NewService("", time.Second*5)
+	if err != nil {
+		t.Error(err)
+	}
+	err = s.FinishInitParams(0, nil)
 	if err != nil {
 		t.FailNow()
 	}
@@ -85,15 +91,18 @@ func TestMultipleInit(t *testing.T) {
 }
 
 func TestUninitialized(t *testing.T) {
-	s := pserver.NewService()
-	err := s.SendGrad(pserver.Gradient{}, nil)
+	s, err := pserver.NewService("", time.Second*5)
+	err = s.SendGrad(pserver.Gradient{}, nil)
 	if err.Error() != pserver.Uninitialized {
 		t.FailNow()
 	}
 }
 
 func TestBlockUntilInitialized(t *testing.T) {
-	s := pserver.NewService()
+	s, err := pserver.NewService("", time.Second*5)
+	if err != nil {
+		t.Error(err)
+	}
 	ch := make(chan struct{}, 2)
 	errCh := make(chan error, 2)
 	var wg sync.WaitGroup
@@ -133,7 +142,7 @@ func TestBlockUntilInitialized(t *testing.T) {
 	p.Name = "param_a"
 	p.Content = []byte{1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0}
 	p.ElementType = pserver.Int32
-	err := s.InitParam(pserver.ParameterWithConfig{Param: p, Config: nil}, nil)
+	err = s.InitParam(pserver.ParameterWithConfig{Param: p, Config: nil}, nil)
 	if err != nil {
 		t.FailNow()
 	}

go/utils/networkhelper/helper.go

@@ -0,0 +1,45 @@
+package networkhelper
+
+import (
+	"errors"
+	"net"
+)
+
+// GetExternalIP returns the ip address of local network interface, not the
+// loopback device.
+func GetExternalIP() (string, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", err
+	}
+	for _, iface := range ifaces {
+		if iface.Flags&net.FlagUp == 0 {
+			continue // interface down
+		}
+		if iface.Flags&net.FlagLoopback != 0 {
+			continue // loopback interface
+		}
+		addrs, err := iface.Addrs()
+		if err != nil {
+			return "", err
+		}
+		for _, addr := range addrs {
+			var ip net.IP
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ip = v.IP
+			case *net.IPAddr:
+				ip = v.IP
+			}
+			if ip == nil || ip.IsLoopback() {
+				continue
+			}
+			ip = ip.To4()
+			if ip == nil {
+				continue // not an ipv4 address
+			}
+			return ip.String(), nil
+		}
+	}
+	return "", errors.New("are you connected to the network?")
+}

go/utils/networkhelper/helper_test.go

@@ -0,0 +1,10 @@
+package networkhelper
+
+import "testing"
+
+func TestGetIP(t *testing.T) {
+	_, err := GetExternalIP()
+	if err != nil {
+		t.Errorf("GetExternalIP returns error : %v\n", err)
+	}
+}