From e2fae1685de73772fb2b46ed67b4ddc0b897c83c Mon Sep 17 00:00:00 2001
From: Helin Wang <ustc.harry@gmail.com>
Date: Fri, 19 May 2017 15:30:53 -0400
Subject: [PATCH] SendGrad will return error if pserver is not initialized.

---
 paddle/go/pserver/service.go      |  7 ++++++-
 paddle/go/pserver/service_test.go | 22 ++++++++++------------
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/paddle/go/pserver/service.go b/paddle/go/pserver/service.go
index a009b4563..f43e59403 100644
--- a/paddle/go/pserver/service.go
+++ b/paddle/go/pserver/service.go
@@ -10,6 +10,7 @@ import (
 type ElementType int
 
 var ErrAlreadyInitialized = errors.New("pserver already initialized")
+var ErrUninitialized = errors.New("pserver not fully initialized")
 
 // Supported element types
 const (
@@ -111,7 +112,11 @@ func (s *Service) FinishInitParams(dummy0 int, dummy1 *int) error {
 // SendGrads sends gradients to parameter servers for parameter
 // optimization.
 func (s *Service) SendGrads(grads []Gradient, dummy *int) error {
-	<-s.initialized
+	select {
+	case <-s.initialized:
+	default:
+		return ErrUninitialized
+	}
 
 	count := len(grads)
 	if count == 0 {
diff --git a/paddle/go/pserver/service_test.go b/paddle/go/pserver/service_test.go
index 6aa7f47c7..10185bd0f 100644
--- a/paddle/go/pserver/service_test.go
+++ b/paddle/go/pserver/service_test.go
@@ -108,9 +108,18 @@ func TestMultipleInit(t *testing.T) {
 	}
 }
 
+func TestUninitialized(t *testing.T) {
+	s := pserver.NewService()
+	var dummy int
+	err := s.SendGrads(nil, &dummy)
+	if err != pserver.ErrUninitialized {
+		t.FailNow()
+	}
+}
+
 func TestBlockUntilInitialized(t *testing.T) {
 	s := pserver.NewService()
-	ch := make(chan struct{}, 3)
+	ch := make(chan struct{}, 2)
 	var wg sync.WaitGroup
 	wg.Add(1)
 	go func() {
@@ -134,17 +143,6 @@ func TestBlockUntilInitialized(t *testing.T) {
 		ch <- struct{}{}
 	}()
 
-	wg.Add(1)
-	go func() {
-		var dummy int
-		err := s.SendGrads(nil, &dummy)
-		if err != nil {
-			t.FailNow()
-		}
-		wg.Done()
-		ch <- struct{}{}
-	}()
-
 	var dummy int
 	err := s.BeginInitParams(nil, &dummy)
 	if err != nil {
-- 
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