Merge pull request #2716 from dzhwinter/save_state

Pserver Save state

go/cmd/pserver/pserver.go

@@ -20,6 +20,8 @@ func main() {
 		"comma separated endpoint string for pserver to connect to etcd")
 	etcdTimeout := flag.Int("etcd-timeout", 5, "timeout for etcd calls")
 	numPservers := flag.Int("num-pservers", 1, "total pserver count in a training job")
+	checkpointPath := flag.String("checkpoint-path", "/checkpoints/", "save checkpoint path")
+	checkpointInterval := flag.Int("checkpoint-interval", 600, "save checkpoint per interval seconds")
 	logLevel := flag.String("log-level", "info",
 		"log level, possible values: debug, info, warning, error, fatal, panic")
 	flag.Parse()
@@ -31,18 +33,20 @@ func main() {
 	log.SetLevel(level)
 
 	var idx int
+	var cp pserver.Checkpoint
+	var e *pserver.EtcdClient
 	if *index >= 0 {
 		idx = *index
 	} else {
 		timeout := time.Second * time.Duration((*etcdTimeout))
-		e := pserver.NewEtcdClient(*etcdEndpoint, *numPservers, timeout)
+		e = pserver.NewEtcdClient(*etcdEndpoint, *numPservers, timeout)
 		idx, err = e.Register()
 		if err != nil {
 			panic(err)
 		}
 	}
 
-	s, err := pserver.NewService(idx)
+	s, err := pserver.NewService(idx, *checkpointInterval, *checkpointPath, e, cp)
 	if err != nil {
 		panic(err)
 	}

go/pserver/etcd_client.go

@@ -18,6 +18,8 @@ const (
 	PsDesired = "/ps_desired"
 	// PsAddr is the base dir for pserver to store their addr
 	PsPath = "/ps/"
+	// PsCheckpoint is the etcd path for store checkpoints information
+	PsCheckpoint = "/checkpoints/"
 )
 
 // EtcdClient is the etcd client that the pserver uses for fault
@@ -186,3 +188,14 @@ func (e *EtcdClient) registerPserverEtcd(ctx context.Context) (int, error) {
 
 	return idx, nil
 }
+
+// PutKey put into etcd with value by key specified
+func (e *EtcdClient) PutKey(key string, value []byte, timeout int) error {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(timeout))
+	_, err := e.etcdClient.Put(ctx, key, string(value))
+	cancel()
+	if err != nil {
+		return err
+	}
+	return nil
+}

go/pserver/optimizer.go

@@ -35,22 +35,28 @@ func cArrayToSlice(p unsafe.Pointer, len int) []byte {
 	return (*[1 << 30]byte)(p)[:len:len]
 }
 
-func newOptimizer(paramWithConfigs ParameterWithConfig) *optimizer {
+func newOptimizer(paramWithConfigs ParameterWithConfig, State []byte) *optimizer {
 	o := &optimizer{}
 	o.elementType = paramWithConfigs.Param.ElementType
 	p := paramWithConfigs.Param
 	c := paramWithConfigs.Config
+	s := State
 	log.WithFields(log.Fields{
 		"ElementType": p.ElementType,
 		"ParamSize":   len(p.Content),
 		"ConfigSize":  len(c),
+		"StateSize":   len(s),
 	}).Info("New Optimizer Created with config:")
 	var cbuffer unsafe.Pointer
 	cbuffer = C.malloc(C.size_t(len(p.Content)))
 	C.memcpy(cbuffer, unsafe.Pointer(&p.Content[0]), C.size_t(len(p.Content)))
+	var cstate unsafe.Pointer
+	if len(s) != 0 {
+		cstate = unsafe.Pointer(&s[0])
+	}
+
 	o.opt = C.paddle_create_optimizer((*C.uchar)(&c[0]), C.int(len(c)),
-		C.paddle_element_type(p.ElementType), cbuffer, C.int(len(p.Content)/C.sizeof_float),
-		(*C.char)(nullPtr), 0)
+		C.paddle_element_type(p.ElementType), cbuffer, C.int(len(p.Content)/C.sizeof_float), (*C.char)(cstate), C.int(len(s)))
 	return o
 }
 
@@ -60,6 +66,12 @@ func (o *optimizer) GetWeights() []byte {
 	return cArrayToSlice(buffer, int(bufferLen)*C.sizeof_float)
 }
 
+func (o *optimizer) GetStates() []byte {
+	var cbuffer *C.char
+	cbuffer_len := C.paddle_optimizer_get_state(o.opt, &cbuffer)
+	return cArrayToSlice(unsafe.Pointer(cbuffer), int(cbuffer_len))
+}
+
 func (o *optimizer) UpdateParameter(g Gradient) error {
 	if o.elementType != g.ElementType {
 		return fmt.Errorf("Name: %s, parameter and gradient element type not match, parameter: %v, gradient: %v", g.Name, o.elementType, g.ElementType)

go/pserver/optimizer_test.go

@@ -19,6 +19,6 @@ func TestOptimizerCreateRelease(t *testing.T) {
 		Param:  p,
 		Config: config,
 	}
-	o := newOptimizer(param)
+	o := newOptimizer(param, nil)
 	o.Cleanup()
 }

go/pserver/service.go

 package pserver
 
 import (
+	"bufio"
+	"bytes"
+	"crypto/md5"
+	"encoding/gob"
+	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
 	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
 )
 
 // ElementType is the type of elements of a Parameter.
@@ -39,26 +51,55 @@ type ParameterWithConfig struct {
 	Config []byte // parameter configuration in Proto Buffer format
 }
 
+// ParameterCheckpoint is Parameter and State checkpoint
+type ParameterCheckpoint struct {
+	ParamConfig ParameterWithConfig
+	State       []byte
+}
+
+// checkpoint signature
+type checkpointMeta struct {
+	UUID      string `json:"uuid"`
+	Md5sum    string `json:"md5sum"`
+	Timestamp string `json:"timestamp"`
+}
+
+// Checkpoint is the pserver shard persist in file
+type Checkpoint []ParameterCheckpoint
+
 // Gradient is the gradient of the parameter.
 type Gradient Parameter
 
 // Service is the RPC service for pserver.
 type Service struct {
-	initialized chan struct{}
-	idx         int
-
-	mu     sync.Mutex
-	optMap map[string]*optimizer
+	initialized        chan struct{}
+	idx                int
+	checkpointInterval time.Duration
+	checkpointPath     string
+	client             *EtcdClient
+	mu                 sync.Mutex
+	optMap             map[string]*optimizer
 }
 
 // NewService creates a new service, will bypass etcd registration if no
 // endpoints specified.
-func NewService(idx int) (*Service, error) {
+func NewService(idx int, seconds int, path string, client *EtcdClient, cp Checkpoint) (*Service, error) {
 	s := &Service{
-		idx: idx,
+		idx:                idx,
+		checkpointInterval: time.Second * time.Duration(seconds),
+		checkpointPath:     path,
+		client:             client,
 	}
 	s.optMap = make(map[string]*optimizer)
 	s.initialized = make(chan struct{})
+
+	if cp != nil {
+		for _, item := range cp {
+			p := item.ParamConfig
+			st := item.State
+			s.optMap[p.Param.Name] = newOptimizer(p, st)
+		}
+	}
 	return s, nil
 }
 
@@ -78,7 +119,7 @@ func (s *Service) InitParam(paramWithConfigs ParameterWithConfig, dummy *int) er
 	// TODO(helin): check if paramWithConfigs.Param.Content is
 	// properly memory aligned, if not, make copy to a memory
 	// aligned region.
-	s.optMap[paramWithConfigs.Param.Name] = newOptimizer(paramWithConfigs)
+	s.optMap[paramWithConfigs.Param.Name] = newOptimizer(paramWithConfigs, nil)
 	return nil
 }
 
@@ -139,10 +180,57 @@ func (s *Service) GetParam(name string, parameter *Parameter) error {
 	return nil
 }
 
-// Save tells the parameter server to save parameters.
-func (s *Service) Save(path string, dummy *int) error {
+// pserver save checkpoint
+func (s *Service) doCheckpoint() error {
 	<-s.initialized
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	cp := make([]ParameterCheckpoint, 0, len(s.optMap))
+	index := 0
+	for name, opt := range s.optMap {
+		var pc ParameterCheckpoint
+		pc.ParamConfig.Param.Name = name
+		pc.ParamConfig.Param.ElementType = opt.elementType
+		pc.ParamConfig.Param.Content = opt.GetWeights()
+		pc.State = opt.GetStates()
+		cp[index] = pc
+		index++
+	}
+	var buf bytes.Buffer
+	encoder := gob.NewEncoder(&buf)
+	err := encoder.Encode(cp)
+	if err != nil {
+		return err
+	}
+
+	cpMeta := checkpointMeta{}
+	cpMeta.UUID = s.checkpointPath + strconv.Itoa(s.idx)
+	cpMeta.Timestamp = time.Now().String()
+	h := md5.New()
+	cpMeta.Md5sum = hex.EncodeToString(h.Sum(buf.Bytes()))
 
-	// TODO
+	cpMetajson, _ := json.Marshal(cpMeta)
+	err = s.client.PutKey(filepath.Join(PsCheckpoint, strconv.Itoa(s.idx)), cpMetajson, 3)
+	if err != nil {
+		return err
+	}
+	if _, err = os.Stat(cpMeta.UUID); os.IsNotExist(err) {
+		log.Info("checkpoint does not exists.")
+	} else {
+		err = os.Remove(cpMeta.UUID)
+		log.Infof("checkpoint %s already exsits, removing ", cpMeta.UUID)
+	}
+	f, err := os.Create(cpMeta.UUID)
+	defer f.Close()
+	if err != nil {
+		return err
+	}
+	writer := bufio.NewWriter(f)
+	_, err = writer.Write(buf.Bytes())
+	writer.Flush()
+	if err != nil {
+		return err
+	}
 	return nil
 }

go/pserver/service_test.go

@@ -15,7 +15,8 @@ const (
 )
 
 func TestServiceFull(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	if err != nil {
 		t.Error(err)
 	}
@@ -86,7 +87,8 @@ func TestServiceFull(t *testing.T) {
 }
 
 func TestMultipleInit(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	if err != nil {
 		t.Error(err)
 	}
@@ -102,7 +104,8 @@ func TestMultipleInit(t *testing.T) {
 }
 
 func TestUninitialized(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	err = s.SendGrad(pserver.Gradient{}, nil)
 	if err.Error() != pserver.Uninitialized {
 		t.FailNow()
@@ -110,7 +113,8 @@ func TestUninitialized(t *testing.T) {
 }
 
 func TestBlockUntilInitialized(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	if err != nil {
 		t.Error(err)
 	}
@@ -128,16 +132,6 @@ func TestBlockUntilInitialized(t *testing.T) {
 		ch <- struct{}{}
 	}()
 
-	wg.Add(1)
-	go func() {
-		err := s.Save("", nil)
-		if err != nil {
-			errCh <- err
-		}
-		wg.Done()
-		ch <- struct{}{}
-	}()
-
 	time.Sleep(50 * time.Millisecond)
 
 	select {
@@ -170,3 +164,7 @@ func TestBlockUntilInitialized(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestCheckpointSpeed(t *testing.T) {
+	//TODO(zhihong): test speed
+}