diff --git a/client/client.go b/client/client.go
index b0265c6..cdfdd5f 100644
--- a/client/client.go
+++ b/client/client.go
@@ -350,16 +350,20 @@ func (client *Client) Status(handle string, timeout time.Duration) (status *Stat
     client.writeJob(newJob(common.REQ, common.GET_STATUS, []byte(handle)))
     select {
     case status = <-client.status:
-    case <-time.NewTimer(timeout).C:
+    case <-time.After(timeout):
         err = common.ErrTimeOut
     }
     return
 }
 
 // Send a something out, get the samething back.
-func (client *Client) Echo(data []byte) (r []byte) {
+func (client *Client) Echo(data []byte, timeout time.Duration) (r []byte, err error) {
     client.writeJob(newJob(common.REQ, common.ECHO_REQ, data))
-    r = <-client.echo
+    select {
+    case r = <-client.echo:
+    case <-time.After(timeout):
+        err = common.ErrTimeOut
+    }
     return
 }
 
diff --git a/client/client_test.go b/client/client_test.go
index e58a71d..11269d7 100644
--- a/client/client_test.go
+++ b/client/client_test.go
@@ -1,6 +1,7 @@
 package client
 
 import (
+    "time"
     "testing"
 )
 
@@ -19,10 +20,14 @@ func TestClientAddServer(t *testing.T) {
 }
 
 func TestClientEcho(t *testing.T) {
-    if echo := string(client.Echo([]byte("Hello world"))); echo == "Hello world" {
-        t.Log(echo)
-    } else {
+    echo, err := client.Echo([]byte("Hello world"), time.Second)
+    if err != nil {
+        t.Error(err)
+        return
+    }
+    if string(echo) != "Hello world" {
         t.Errorf("Invalid echo data: %s", echo)
+        return
     }
 }
 
@@ -30,8 +35,6 @@ func TestClientDoBg(t *testing.T) {
     if handle := client.DoBg("ToUpper", []byte("abcdef"),
         JOB_LOW); handle == "" {
         t.Error("Handle is empty.")
-    } else {
-        t.Log(handle)
     }
 }
 
@@ -55,21 +58,33 @@ func TestClientDo(t *testing.T) {
 
 func TestClientStatus(t *testing.T) {
 
-    s1 := client.Status("handle not exists")
+    s1, err := client.Status("handle not exists", time.Second)
+    if err != nil {
+        t.Error(err)
+        return
+    }
     if s1.Known {
         t.Errorf("The job (%s) shouldn't be known.", s1.Handle)
+        return
     }
     if s1.Running {
         t.Errorf("The job (%s) shouldn't be running.", s1.Handle)
+        return
     }
 
     handle := client.Do("Delay5sec", []byte("abcdef"), JOB_LOW, nil);
-    s2 := client.Status(handle)
+    s2, err := client.Status(handle, time.Second)
+    if err != nil {
+        t.Error(err)
+        return
+    }
     if !s2.Known {
         t.Errorf("The job (%s) should be known.", s2.Handle)
+        return
     }
     if s2.Running {
         t.Errorf("The job (%s) shouldn't be running.", s2.Handle)
+        return
     }
 }
 
diff --git a/client/pool.go b/client/pool.go
index 894cf56..ed48734 100644
--- a/client/pool.go
+++ b/client/pool.go
@@ -85,7 +85,6 @@ func (pool *Pool) Add(addr string, rate int) (err error) {
         var client *Client
         client, err = New(addr)
         item = &poolClient{Client: client, Rate: rate}
-        err = item.connect()
         pool.clients[addr] = item
     }
     return
@@ -126,7 +125,7 @@ func (pool *Pool) Status(addr, handle string, timeout time.Duration) (status *St
 }
 
 // Send a something out, get the samething back.
-func (pool *Pool) Echo(addr string, data []byte) (r []byte, err error) {
+func (pool *Pool) Echo(addr string, data []byte, timeout time.Duration) (r []byte, err error) {
     var client *poolClient
     if addr == "" {
         client = pool.selectServer()
@@ -137,7 +136,7 @@ func (pool *Pool) Echo(addr string, data []byte) (r []byte, err error) {
             return
         }
     }
-    r = client.Echo(data)
+    r, err = client.Echo(data, timeout)
     return
 }
 
diff --git a/client/pool_test.go b/client/pool_test.go
index bf21f0c..227c1f0 100644
--- a/client/pool_test.go
+++ b/client/pool_test.go
@@ -1,6 +1,7 @@
 package client
 
 import (
+    "time"
     "testing"
 )
 
@@ -22,17 +23,17 @@ func TestPoolAdd(t *testing.T) {
 }
 
 func TestPoolEcho(t *testing.T) {
-    echo, err := pool.Echo("", []byte("Hello world"))
+    echo, err := pool.Echo("", []byte("Hello pool"), time.Second)
     if err != nil {
         t.Error(err)
         return
     }
-    if string(echo) != "Hello world" {
+    if string(echo) != "Hello pool" {
         t.Errorf("Invalid echo data: %s", echo)
         return
     }
 
-    _, err = pool.Echo("not exists", []byte("Hello world"))
+    _, err = pool.Echo("not exists", []byte("Hello pool"), time.Second)
     if err != ErrNotFound {
         t.Errorf("ErrNotFound expected, got %s", err)
     }
@@ -66,7 +67,7 @@ func TestPoolDo(t *testing.T) {
 }
 
 func TestPoolStatus(t *testing.T) {
-    s1, err := pool.Status("127.0.0.1:4730", "handle not exists")
+    s1, err := pool.Status("127.0.0.1:4730", "handle not exists", time.Second)
     if err != nil {
         t.Error(err)
         return
@@ -79,7 +80,7 @@ func TestPoolStatus(t *testing.T) {
     }
 
     addr, handle := pool.Do("Delay5sec", []byte("abcdef"), JOB_LOW, nil);
-    s2, err := pool.Status(addr, handle)
+    s2, err := pool.Status(addr, handle, time.Second)
     if err != nil {
         t.Error(err)
         return
@@ -92,7 +93,7 @@ func TestPoolStatus(t *testing.T) {
         t.Errorf("The job (%s) shouldn't be running.", s2.Handle)
     }
 
-    _, err = pool.Status("not exists", "not exists")
+    _, err = pool.Status("not exists", "not exists", time.Second)
     if err != ErrNotFound {
         t.Error(err)
     }
diff --git a/example/client.go b/example/client.go
index d377312..cce04dc 100644
--- a/example/client.go
+++ b/example/client.go
@@ -24,7 +24,11 @@ func main() {
     }
     echo := []byte("Hello\x00 world")
     wg.Add(1)
-    log.Println(string(c.Echo(echo)))
+    echomsg, err := c.Echo(echo, time.Second)
+    if err != nil {
+        log.Fatalln(err)
+    }
+    log.Println(string(echomsg))
     wg.Done()
     jobHandler := func(job *client.Job) {
         log.Printf("%s", job.Data)
diff --git a/example/worker b/example/worker
deleted file mode 100755
index 0558732..0000000
Binary files a/example/worker and /dev/null differ
diff --git a/worker/agent.go b/worker/agent.go
index 1e17584..fbc8c76 100644
--- a/worker/agent.go
+++ b/worker/agent.go
@@ -91,8 +91,11 @@ func (a *agent) inLoop() {
         case common.NOOP:
             a.WriteJob(newJob(common.REQ, common.GRAB_JOB_UNIQ, nil))
         case common.ERROR, common.ECHO_RES, common.JOB_ASSIGN_UNIQ, common.JOB_ASSIGN:
-            job.agent = a
             if a.worker.running {
+                if a.worker.limit != nil {
+                    a.worker.limit <- true
+                }
+                job.agent = a
                 a.worker.in <- job
             }
         }
diff --git a/worker/job.go b/worker/job.go
index 361fdce..6f86989 100644
--- a/worker/job.go
+++ b/worker/job.go
@@ -110,7 +110,7 @@ func (job *Job) UpdateData(data []byte, iswarning bool) {
 func (job *Job) UpdateStatus(numerator, denominator int) {
     n := []byte(strconv.Itoa(numerator))
     d := []byte(strconv.Itoa(denominator))
-    result := append([]byte(job.Handle), 0)
+    result := append([]byte(job.Handle), '\x00')
     result = append(result, n...)
     result = append(result, '\x00')
     result = append(result, d...)
diff --git a/worker/worker.go b/worker/worker.go
index 7ad830d..e96118c 100644
--- a/worker/worker.go
+++ b/worker/worker.go
@@ -73,9 +73,6 @@ func New(l int) (worker *Worker) {
     }
     if l != Unlimited {
         worker.limit = make(chan bool, l)
-        for i := 0; i < l; i ++ {
-            worker.limit <- true
-        }
     }
     return
 }
@@ -165,7 +162,7 @@ func (worker *Worker) dealJob(job *Job) {
     defer func() {
         job.Close()
         if worker.running && worker.limit != nil {
-            worker.limit <- true
+            <-worker.limit
         }
     }()
     switch job.DataType {
@@ -199,9 +196,6 @@ func (worker *Worker) Work() {
     for ok {
         var job *Job
         if job, ok = <-worker.in; ok {
-            if worker.limit != nil {
-                <-worker.limit
-            }
             go worker.dealJob(job)
         }
     }