diff --git a/ants.go b/ants.go
index a0f4aa9..f22782e 100644
--- a/ants.go
+++ b/ants.go
@@ -65,6 +65,7 @@ func Release() {
 
 // Errors for the Ants API
 var (
-	ErrPoolSizeInvalid = errors.New("invalid size for pool")
-	ErrPoolClosed      = errors.New("this pool has been closed")
+	ErrInvalidPoolSize   = errors.New("invalid size for pool")
+	ErrInvalidPoolExpiry = errors.New("invalid expiry for pool")
+	ErrPoolClosed        = errors.New("this pool has been closed")
 )
diff --git a/ants_benchmark_test.go b/ants_benchmark_test.go
index ef070fd..7ef3e89 100644
--- a/ants_benchmark_test.go
+++ b/ants_benchmark_test.go
@@ -41,8 +41,11 @@ const (
 	ZiB // 1180591620717411303424    (超过了int64的范围)
 	YiB // 1208925819614629174706176
 )
-const RunTimes = 1000000
-const loop = 10
+const (
+	RunTimes = 1000000
+	Param    = 10
+	AntsSize = 100000
+)
 
 func demoFunc() error {
 	n := 10
@@ -68,7 +71,7 @@ func BenchmarkGoroutineWithFunc(b *testing.B) {
 		for j := 0; j < RunTimes; j++ {
 			wg.Add(1)
 			go func() {
-				demoPoolFunc(loop)
+				demoPoolFunc(Param)
 				wg.Done()
 			}()
 		}
@@ -78,7 +81,7 @@ func BenchmarkGoroutineWithFunc(b *testing.B) {
 
 func BenchmarkAntsPoolWithFunc(b *testing.B) {
 	var wg sync.WaitGroup
-	p, _ := ants.NewPoolWithFunc(50000, func(i interface{}) error {
+	p, _ := ants.NewPoolWithFunc(AntsSize, func(i interface{}) error {
 		demoPoolFunc(i)
 		wg.Done()
 		return nil
@@ -88,7 +91,7 @@ func BenchmarkAntsPoolWithFunc(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		for j := 0; j < RunTimes; j++ {
 			wg.Add(1)
-			p.Serve(loop)
+			p.Serve(Param)
 		}
 		wg.Wait()
 		b.Logf("running goroutines: %d", p.Running())
@@ -98,19 +101,19 @@ func BenchmarkAntsPoolWithFunc(b *testing.B) {
 func BenchmarkGoroutine(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		for j := 0; j < RunTimes; j++ {
-			go demoPoolFunc(loop)
+			go demoPoolFunc(Param)
 		}
 	}
 }
 
 func BenchmarkAntsPool(b *testing.B) {
-	p, _ := ants.NewPoolWithFunc(50000, demoPoolFunc)
+	p, _ := ants.NewPoolWithFunc(AntsSize, demoPoolFunc)
 	defer p.Release()
 
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		for j := 0; j < RunTimes; j++ {
-			p.Serve(loop)
+			p.Serve(Param)
 		}
 		// b.Logf("running goroutines: %d", p.Running())
 	}
diff --git a/pool.go b/pool.go
index 79a2afb..d5069ef 100644
--- a/pool.go
+++ b/pool.go
@@ -95,7 +95,10 @@ func NewPool(size int) (*Pool, error) {
 // NewTimingPool generates a instance of ants pool with a custom timed task
 func NewTimingPool(size, expiry int) (*Pool, error) {
 	if size <= 0 {
-		return nil, ErrPoolSizeInvalid
+		return nil, ErrInvalidPoolSize
+	}
+	if expiry <= 0 {
+		return nil, ErrInvalidPoolExpiry
 	}
 	p := &Pool{
 		capacity:       int32(size),
diff --git a/pool_func.go b/pool_func.go
index f9ac15b..b2ef61e 100644
--- a/pool_func.go
+++ b/pool_func.go
@@ -66,7 +66,6 @@ func (p *PoolWithFunc) monitorAndClear() {
 	heartbeat := time.NewTicker(p.expiryDuration)
 	go func() {
 		for range heartbeat.C {
-			time.Sleep(p.expiryDuration)
 			currentTime := time.Now()
 			p.lock.Lock()
 			idleWorkers := p.workers
@@ -81,7 +80,7 @@ func (p *PoolWithFunc) monitorAndClear() {
 				p.running--
 			}
 			if n > 0 {
-				n += 1
+				n++
 				p.workers = idleWorkers[n:]
 			}
 			p.lock.Unlock()
@@ -97,7 +96,10 @@ func NewPoolWithFunc(size int, f pf) (*PoolWithFunc, error) {
 // NewTimingPoolWithFunc generates a instance of ants pool with a specific function and a custom timed task
 func NewTimingPoolWithFunc(size, expiry int, f pf) (*PoolWithFunc, error) {
 	if size <= 0 {
-		return nil, ErrPoolSizeInvalid
+		return nil, ErrInvalidPoolSize
+	}
+	if expiry <= 0 {
+		return nil, ErrInvalidPoolExpiry
 	}
 	p := &PoolWithFunc{
 		capacity:       int32(size),