diff --git a/.travis.yml b/.travis.yml
index c7e9cc6..9c67cfc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,12 @@ go:
   - "1.10.x"
   - master
 
+before_install:
+  - go get -t -v ./...
+
 script:
-  - go test -v ./...
-  - go test -bench=. -benchmem=true -run=none ./...
\ No newline at end of file
+  - go test -race -coverprofile=coverage.txt -covermode=atomic
+#  - go test -bench=. -benchmem=true -run=none ./...
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)
\ No newline at end of file
diff --git a/README.md b/README.md
index d4e94b2..e5e3b39 100644
--- a/README.md
+++ b/README.md
@@ -6,9 +6,10 @@
 
 
 [![Build Status][1]][2]
-[![godoc for panjf2000/ants][3]][4]
+[![codecov][3]][4]
 [![goreportcard for panjf2000/ants][5]][6]
-[![MIT Licence][7]][8]
+[![godoc for panjf2000/ants][7]][8]
+[![MIT Licence][9]][10]
 
 [中文项目说明](README_ZH.md) | [Project Tutorial](http://blog.taohuawu.club/article/42)
 
@@ -185,9 +186,11 @@ There was only the test of `ants` Pool because my computer was crash when it rea
 
 [1]: https://travis-ci.com/panjf2000/ants.svg?branch=master
 [2]: https://travis-ci.com/panjf2000/ants
-[3]: https://godoc.org/github.com/panjf2000/ants?status.svg
-[4]: https://godoc.org/github.com/panjf2000/ants
+[3]: https://codecov.io/gh/panjf2000/ants/branch/develop/graph/badge.svg
+[4]: https://codecov.io/gh/panjf2000/ants
 [5]: https://goreportcard.com/badge/github.com/panjf2000/ants
 [6]: https://goreportcard.com/report/github.com/panjf2000/ants
-[7]: https://badges.frapsoft.com/os/mit/mit.svg?v=103
-[8]: https://opensource.org/licenses/mit-license.php
+[7]: https://godoc.org/github.com/panjf2000/ants?status.svg
+[8]: https://godoc.org/github.com/panjf2000/ants
+[9]: https://badges.frapsoft.com/os/mit/mit.svg?v=103
+[10]: https://opensource.org/licenses/mit-license.php
diff --git a/ants_benchmark_test.go b/ants_benchmark_test.go
index 7ef3e89..440a3c8 100644
--- a/ants_benchmark_test.go
+++ b/ants_benchmark_test.go
@@ -42,9 +42,9 @@ const (
 	YiB // 1208925819614629174706176
 )
 const (
-	RunTimes = 1000000
+	RunTimes = 10000000
 	Param    = 10
-	AntsSize = 100000
+	AntsSize = 50000
 )
 
 func demoFunc() error {
diff --git a/ants_test.go b/ants_test.go
index 11059ec..72250b4 100644
--- a/ants_test.go
+++ b/ants_test.go
@@ -32,7 +32,27 @@ import (
 
 var n = 1000000
 
-func TestDefaultPool(t *testing.T) {
+func TestAntsPoolWithFunc(t *testing.T) {
+	var wg sync.WaitGroup
+	p, _ := ants.NewPoolWithFunc(AntsSize, func(i interface{}) error {
+		demoPoolFunc(i)
+		wg.Done()
+		return nil
+	})
+	defer p.Release()
+
+	for i := 0; i < n; i++ {
+		wg.Add(1)
+		p.Serve(Param)
+	}
+	wg.Wait()
+
+	mem := runtime.MemStats{}
+	runtime.ReadMemStats(&mem)
+	t.Logf("memory usage:%d", mem.TotalAlloc/GiB)
+}
+
+func TestAntsPool(t *testing.T) {
 	defer ants.Release()
 	var wg sync.WaitGroup
 	for i := 0; i < n; i++ {
@@ -45,10 +65,10 @@ func TestDefaultPool(t *testing.T) {
 	}
 	wg.Wait()
 
-	//t.Logf("pool capacity:%d", ants.Cap())
-	//t.Logf("free workers number:%d", ants.Free())
+	t.Logf("pool, capacity:%d", ants.Cap())
+	t.Logf("pool, running workers number:%d", ants.Running())
+	t.Logf("pool, free workers number:%d", ants.Free())
 
-	t.Logf("running workers number:%d", ants.Running())
 	mem := runtime.MemStats{}
 	runtime.ReadMemStats(&mem)
 	t.Logf("memory usage:%d MB", mem.TotalAlloc/MiB)
@@ -70,27 +90,42 @@ func TestNoPool(t *testing.T) {
 	t.Logf("memory usage:%d MB", mem.TotalAlloc/MiB)
 }
 
-// func TestAntsPoolWithFunc(t *testing.T) {
-// 	var wg sync.WaitGroup
-// 	p, _ := ants.NewPoolWithFunc(50000, func(i interface{}) error {
-// 		demoPoolFunc(i)
-// 		wg.Done()
-// 		return nil
-// 	})
-// 	for i := 0; i < n; i++ {
-// 		wg.Add(1)
-// 		p.Serve(n)
-// 	}
-// 	wg.Wait()
+func TestCodeCov(t *testing.T) {
+	_, err := ants.NewTimingPool(-1, -1)
+	t.Log(err)
+	_, err = ants.NewTimingPool(1, -1)
+	t.Log(err)
+	_, err = ants.NewTimingPoolWithFunc(-1, -1, demoPoolFunc)
+	t.Log(err)
+	_, err = ants.NewTimingPoolWithFunc(1, -1, demoPoolFunc)
+	t.Log(err)
 
-// 	//t.Logf("pool capacity:%d", ants.Cap())
-// 	//t.Logf("free workers number:%d", ants.Free())
+	p0, _ := ants.NewPool(AntsSize)
+	defer p0.Submit(demoFunc)
+	defer p0.Release()
+	for i := 0; i < n; i++ {
+		p0.Submit(demoFunc)
+	}
+	t.Logf("pool, capacity:%d", p0.Cap())
+	t.Logf("pool, running workers number:%d", p0.Running())
+	t.Logf("pool, free workers number:%d", p0.Free())
+	p0.ReSize(AntsSize)
+	p0.ReSize(AntsSize / 2)
+	t.Logf("pool, after resize, capacity:%d", p0.Cap())
 
-// 	t.Logf("running workers number:%d", p.Running())
-// 	mem := runtime.MemStats{}
-// 	runtime.ReadMemStats(&mem)
-// 	t.Logf("memory usage:%d", mem.TotalAlloc/GiB)
-// }
+	p, _ := ants.NewPoolWithFunc(AntsSize, demoPoolFunc)
+	defer p.Serve(Param)
+	defer p.Release()
+	for i := 0; i < n; i++ {
+		p.Serve(Param)
+	}
+	t.Logf("pool with func, capacity:%d", p.Cap())
+	t.Logf("pool with func, running workers number:%d", p.Running())
+	t.Logf("pool with func, free workers number:%d", p.Free())
+	p.ReSize(AntsSize)
+	p.ReSize(AntsSize / 2)
+	t.Logf("pool with func, after resize, capacity:%d", p.Cap())
+}
 
 // func TestNoPool(t *testing.T) {
 // 	var wg sync.WaitGroup
diff --git a/pool.go b/pool.go
index 53471e2..3f988aa 100644
--- a/pool.go
+++ b/pool.go
@@ -76,7 +76,7 @@ func (p *Pool) monitorAndClear() {
 				n = i
 				w.task <- nil
 				idleWorkers[i] = nil
-				p.running--
+				atomic.AddInt32(&p.running, 1)
 			}
 			if n > 0 {
 				n++
@@ -145,10 +145,9 @@ func (p *Pool) Release() error {
 		for i := 0; i < running; i++ {
 			p.getWorker().task <- nil
 		}
-		for i := range p.workers {
-			p.workers[i] = nil
-		}
+		p.lock.Lock()
 		p.workers = nil
+		p.lock.Unlock()
 	})
 	return nil
 }
@@ -177,10 +176,10 @@ func (p *Pool) getWorker() *Worker {
 	workers := p.workers
 	n := len(workers) - 1
 	if n < 0 {
-		if p.running >= p.capacity {
+		if p.Running() >= p.Cap() {
 			waiting = true
 		} else {
-			p.running++
+			atomic.AddInt32(&p.running, 1)
 		}
 	} else {
 		<-p.freeSignal
diff --git a/pool_func.go b/pool_func.go
index d99269f..c4dea88 100644
--- a/pool_func.go
+++ b/pool_func.go
@@ -77,7 +77,7 @@ func (p *PoolWithFunc) monitorAndClear() {
 				n = i
 				w.args <- nil
 				idleWorkers[i] = nil
-				p.running--
+				atomic.AddInt32(&p.running, 1)
 			}
 			if n > 0 {
 				n++
@@ -150,10 +150,9 @@ func (p *PoolWithFunc) Release() error {
 		for i := 0; i < running; i++ {
 			p.getWorker().args <- nil
 		}
-		for i := range p.workers {
-			p.workers[i] = nil
-		}
+		p.lock.Lock()
 		p.workers = nil
+		p.lock.Unlock()
 	})
 	return nil
 }
@@ -182,10 +181,10 @@ func (p *PoolWithFunc) getWorker() *WorkerWithFunc {
 	workers := p.workers
 	n := len(workers) - 1
 	if n < 0 {
-		if p.running >= p.capacity {
+		if p.Running() >= p.Cap() {
 			waiting = true
 		} else {
-			p.running++
+			atomic.AddInt32(&p.running, 1)
 		}
 	} else {
 		<-p.freeSignal