diff --git a/metric.go b/metric.go
index e9ff253..a75fbbd 100644
--- a/metric.go
+++ b/metric.go
@@ -6,22 +6,25 @@ import "sync/atomic"
 type Metric interface {
 	IncBusyWorker()
 	DecBusyWorker()
-	BusyWorkers() uint64
+	BusyWorkers() int64
 	SuccessTasks() uint64
 	FailureTasks() uint64
 	SubmittedTasks() uint64
+	CompletedTasks() uint64
 	IncSuccessTask()
 	IncFailureTask()
 	IncSubmittedTask()
+	IncCompletedTask()
 }
 
 var _ Metric = (*metric)(nil)
 
 type metric struct {
-	busyWorkers    uint64
+	busyWorkers    int64
 	successTasks   uint64
 	failureTasks   uint64
 	submittedTasks uint64
+	completedTasks uint64
 }
 
 // NewMetric for default metric structure
@@ -30,15 +33,15 @@ func NewMetric() Metric {
 }
 
 func (m *metric) IncBusyWorker() {
-	atomic.AddUint64(&m.busyWorkers, 1)
+	atomic.AddInt64(&m.busyWorkers, 1)
 }
 
 func (m *metric) DecBusyWorker() {
-	atomic.AddUint64(&m.busyWorkers, ^uint64(0))
+	atomic.AddInt64(&m.busyWorkers, ^int64(0))
 }
 
-func (m *metric) BusyWorkers() uint64 {
-	return atomic.LoadUint64(&m.busyWorkers)
+func (m *metric) BusyWorkers() int64 {
+	return atomic.LoadInt64(&m.busyWorkers)
 }
 
 func (m *metric) IncSuccessTask() {
@@ -53,6 +56,10 @@ func (m *metric) IncSubmittedTask() {
 	atomic.AddUint64(&m.submittedTasks, 1)
 }
 
+func (m *metric) IncCompletedTask() {
+	atomic.AddUint64(&m.completedTasks, 1)
+}
+
 func (m *metric) SuccessTasks() uint64 {
 	return atomic.LoadUint64(&m.successTasks)
 }
@@ -64,3 +71,7 @@ func (m *metric) FailureTasks() uint64 {
 func (m *metric) SubmittedTasks() uint64 {
 	return atomic.LoadUint64(&m.submittedTasks)
 }
+
+func (m *metric) CompletedTasks() uint64 {
+	return atomic.LoadUint64(&m.completedTasks)
+}
diff --git a/metric_test.go b/metric_test.go
index 1105756..4073633 100644
--- a/metric_test.go
+++ b/metric_test.go
@@ -44,8 +44,8 @@ func TestMetricData(t *testing.T) {
 	}))
 	q.Start()
 	time.Sleep(50 * time.Millisecond)
-	assert.Equal(t, 4, q.SubmittedTasks())
-	assert.Equal(t, 2, q.SuccessTasks())
-	assert.Equal(t, 2, q.FailureTasks())
+	assert.Equal(t, uint64(4), q.SubmittedTasks())
+	assert.Equal(t, uint64(2), q.SuccessTasks())
+	assert.Equal(t, uint64(2), q.FailureTasks())
 	q.Release()
 }
diff --git a/options.go b/options.go
index 9fa2492..0690d17 100644
--- a/options.go
+++ b/options.go
@@ -9,7 +9,7 @@ import (
 
 var (
 	defaultCapacity    = 0
-	defaultWorkerCount = runtime.NumCPU()
+	defaultWorkerCount = int64(runtime.NumCPU())
 	defaultNewLogger   = NewLogger()
 	defaultFn          = func(context.Context, core.QueuedMessage) error { return nil }
 	defaultMetric      = NewMetric()
@@ -29,7 +29,7 @@ func (f OptionFunc) apply(option *Options) {
 }
 
 // WithWorkerCount set worker count
-func WithWorkerCount(num int) Option {
+func WithWorkerCount(num int64) Option {
 	return OptionFunc(func(q *Options) {
 		if num <= 0 {
 			num = defaultWorkerCount
@@ -82,7 +82,7 @@ func WithAfterFn(afterFn func()) Option {
 
 // Options for custom args in Queue
 type Options struct {
-	workerCount int
+	workerCount int64
 	logger      Logger
 	queueSize   int
 	worker      core.Worker
diff --git a/pool.go b/pool.go
index 6790b76..49dcd33 100644
--- a/pool.go
+++ b/pool.go
@@ -1,7 +1,7 @@
 package queue
 
 // NewPool initializes a new pool
-func NewPool(size int, opts ...Option) *Queue {
+func NewPool(size int64, opts ...Option) *Queue {
 	o := []Option{
 		WithWorkerCount(size),
 		WithWorker(NewRing(opts...)),
diff --git a/pool_test.go b/pool_test.go
index e4e2626..f7816c6 100644
--- a/pool_test.go
+++ b/pool_test.go
@@ -8,7 +8,7 @@ import (
 )
 
 func TestNewPoolWithQueueTask(t *testing.T) {
-	totalN := 5
+	totalN := int64(5)
 	taskN := 100
 	rets := make(chan struct{}, taskN)
 
@@ -26,7 +26,7 @@ func TestNewPoolWithQueueTask(t *testing.T) {
 
 	// shutdown all, and now running worker is 0
 	p.Release()
-	assert.Equal(t, 0, p.BusyWorkers())
+	assert.Equal(t, int64(0), p.BusyWorkers())
 }
 
 func TestPoolNumber(t *testing.T) {
@@ -34,5 +34,5 @@ func TestPoolNumber(t *testing.T) {
 	p.Start()
 	// shutdown all, and now running worker is 0
 	p.Release()
-	assert.Equal(t, 0, p.BusyWorkers())
+	assert.Equal(t, int64(0), p.BusyWorkers())
 }
diff --git a/queue.go b/queue.go
index 9dc1df8..78223cd 100644
--- a/queue.go
+++ b/queue.go
@@ -22,7 +22,7 @@ type (
 		sync.Mutex
 		metric       *metric
 		logger       Logger
-		workerCount  int
+		workerCount  int64
 		routineGroup *routineGroup
 		quit         chan struct{}
 		ready        chan struct{}
@@ -95,23 +95,28 @@ func (q *Queue) Release() {
 }
 
 // BusyWorkers returns the numbers of workers in the running process.
-func (q *Queue) BusyWorkers() int {
-	return int(q.metric.BusyWorkers())
+func (q *Queue) BusyWorkers() int64 {
+	return q.metric.BusyWorkers()
 }
 
 // BusyWorkers returns the numbers of success tasks.
-func (q *Queue) SuccessTasks() int {
-	return int(q.metric.SuccessTasks())
+func (q *Queue) SuccessTasks() uint64 {
+	return q.metric.SuccessTasks()
 }
 
 // BusyWorkers returns the numbers of failure tasks.
-func (q *Queue) FailureTasks() int {
-	return int(q.metric.FailureTasks())
+func (q *Queue) FailureTasks() uint64 {
+	return q.metric.FailureTasks()
 }
 
 // BusyWorkers returns the numbers of submitted tasks.
-func (q *Queue) SubmittedTasks() int {
-	return int(q.metric.SubmittedTasks())
+func (q *Queue) SubmittedTasks() uint64 {
+	return q.metric.SubmittedTasks()
+}
+
+// CompletedTasks returns the numbers of completed tasks.
+func (q *Queue) CompletedTasks() uint64 {
+	return q.metric.CompletedTasks()
 }
 
 // Wait all process
@@ -269,7 +274,7 @@ func (q *Queue) handle(m *job.Message) error {
 }
 
 // UpdateWorkerCount to update worker number dynamically.
-func (q *Queue) UpdateWorkerCount(num int) {
+func (q *Queue) UpdateWorkerCount(num int64) {
 	q.Lock()
 	q.workerCount = num
 	q.Unlock()
diff --git a/queue_test.go b/queue_test.go
index c97e221..d9ede90 100644
--- a/queue_test.go
+++ b/queue_test.go
@@ -48,7 +48,7 @@ func TestNewQueueWithZeroWorker(t *testing.T) {
 
 	q.Start()
 	time.Sleep(50 * time.Millisecond)
-	assert.Equal(t, 0, q.BusyWorkers())
+	assert.Equal(t, int64(0), q.BusyWorkers())
 	q.Release()
 }
 
@@ -74,7 +74,7 @@ func TestNewQueueWithDefaultWorker(t *testing.T) {
 
 	q.Start()
 	q.Release()
-	assert.Equal(t, 0, q.BusyWorkers())
+	assert.Equal(t, int64(0), q.BusyWorkers())
 }
 
 func TestHandleTimeout(t *testing.T) {
diff --git a/ring_test.go b/ring_test.go
index 996e9f8..aa93fd7 100644
--- a/ring_test.go
+++ b/ring_test.go
@@ -142,7 +142,7 @@ func TestCancelJobAfterShutdown(t *testing.T) {
 	assert.NoError(t, q.Queue(m, job.AllowOption{Timeout: job.Time(100 * time.Millisecond)}))
 	q.Start()
 	time.Sleep(10 * time.Millisecond)
-	assert.Equal(t, 2, q.BusyWorkers())
+	assert.Equal(t, int64(2), q.BusyWorkers())
 	q.Release()
 }
 
@@ -231,10 +231,10 @@ func TestIncreaseWorkerCount(t *testing.T) {
 
 	q.Start()
 	time.Sleep(100 * time.Millisecond)
-	assert.Equal(t, 5, q.BusyWorkers())
+	assert.Equal(t, int64(5), q.BusyWorkers())
 	q.UpdateWorkerCount(10)
 	time.Sleep(100 * time.Millisecond)
-	assert.Equal(t, 10, q.BusyWorkers())
+	assert.Equal(t, int64(10), q.BusyWorkers())
 	q.Release()
 }
 
@@ -261,12 +261,12 @@ func TestDecreaseWorkerCount(t *testing.T) {
 
 	q.Start()
 	time.Sleep(20 * time.Millisecond)
-	assert.Equal(t, 5, q.BusyWorkers())
+	assert.Equal(t, int64(5), q.BusyWorkers())
 	q.UpdateWorkerCount(3)
 	time.Sleep(100 * time.Millisecond)
-	assert.Equal(t, 3, q.BusyWorkers())
+	assert.Equal(t, int64(3), q.BusyWorkers())
 	time.Sleep(100 * time.Millisecond)
-	assert.Equal(t, 2, q.BusyWorkers())
+	assert.Equal(t, int64(2), q.BusyWorkers())
 	q.Release()
 }