diff --git a/queue/queue.go b/queue/queue.go
index 0b54a4d..38600cd 100644
--- a/queue/queue.go
+++ b/queue/queue.go
@@ -63,14 +63,25 @@ func (q *Queue) Queue(job interface{}) error {
 	return q.worker.Queue(job)
 }
 
+func (q *Queue) work(num int) {
+	q.routineGroup.Run(func() {
+		// to handle panic cases from inside the worker
+		// in such case, we start a new goroutine
+		defer func() {
+			if err := recover(); err != nil {
+				logx.LogError.Error(err)
+				go q.work(num)
+			}
+		}()
+
+		logx.LogAccess.Info("started the worker num ", num)
+		q.worker.Run(q.quit)
+		logx.LogAccess.Info("closed the worker num ", num)
+	})
+}
+
 func (q *Queue) startWorker() {
 	for i := 0; i < q.workerCount; i++ {
-		go func(num int) {
-			q.routineGroup.Run(func() {
-				logx.LogAccess.Info("started the worker num ", num)
-				q.worker.Run(q.quit)
-				logx.LogAccess.Info("closed the worker num ", num)
-			})
-		}(i)
+		go q.work(i)
 	}
 }
diff --git a/queue/simple/simple.go b/queue/simple/simple.go
index 6603ea5..ea8d611 100644
--- a/queue/simple/simple.go
+++ b/queue/simple/simple.go
@@ -13,6 +13,8 @@ var _ queue.Worker = (*Worker)(nil)
 // Option for queue system
 type Option func(*Worker)
 
+var errMaxCapacity = errors.New("max capacity reached")
+
 // Worker for simple queue using channel
 type Worker struct {
 	queueNotification chan gorush.PushNotification
@@ -49,7 +51,7 @@ func (s *Worker) Queue(job interface{}) error {
 	case s.queueNotification <- job.(gorush.PushNotification):
 		return nil
 	default:
-		return errors.New("max capacity reached")
+		return errMaxCapacity
 	}
 }
 
diff --git a/queue/simple/simple_test.go b/queue/simple/simple_test.go
new file mode 100644
index 0000000..c739ae8
--- /dev/null
+++ b/queue/simple/simple_test.go
@@ -0,0 +1,34 @@
+package simple
+
+import (
+	"runtime"
+	"testing"
+
+	"github.com/appleboy/gorush/gorush"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestQueueUsage(t *testing.T) {
+	w := NewWorker()
+	assert.Equal(t, runtime.NumCPU()<<1, w.Capacity())
+	assert.Equal(t, 0, w.Usage())
+
+	w.Queue(gorush.PushNotification{})
+	assert.Equal(t, 1, w.Usage())
+}
+
+func TestMaxCapacity(t *testing.T) {
+	w := NewWorker(WithQueueNum(2))
+	assert.Equal(t, 2, w.Capacity())
+	assert.Equal(t, 0, w.Usage())
+
+	assert.NoError(t, w.Queue(gorush.PushNotification{}))
+	assert.Equal(t, 1, w.Usage())
+	assert.NoError(t, w.Queue(gorush.PushNotification{}))
+	assert.Equal(t, 2, w.Usage())
+	assert.Error(t, w.Queue(gorush.PushNotification{}))
+	assert.Equal(t, 2, w.Usage())
+
+	err := w.Queue(gorush.PushNotification{})
+	assert.Equal(t, errMaxCapacity, err)
+}