diff --git a/ants.go b/ants.go
index b55872e..335ac87 100644
--- a/ants.go
+++ b/ants.go
@@ -1,6 +1,6 @@
 package ants
 
-const DEFAULT_POOL_SIZE = 5
+const DEFAULT_POOL_SIZE = 50000
 
 var defaultPool = NewPool(DEFAULT_POOL_SIZE)
 
diff --git a/ants_benchmark_test.go b/ants_benchmark_test.go
index be54823..274ba1c 100644
--- a/ants_benchmark_test.go
+++ b/ants_benchmark_test.go
@@ -6,7 +6,7 @@ import (
 	"sync"
 )
 
-const RunTimes = 10
+const RunTimes = 10000000
 
 func BenchmarkGoroutine(b *testing.B) {
 	for i := 0; i < b.N; i++ {
diff --git a/pool.go b/pool.go
index 8eb4215..a7ee612 100644
--- a/pool.go
+++ b/pool.go
@@ -4,6 +4,7 @@ import (
 	"runtime"
 	"sync/atomic"
 	"sync"
+	"math"
 )
 
 type sig struct{}
@@ -17,13 +18,13 @@ type Pool struct {
 	workers    []*Worker
 	workerPool sync.Pool
 	destroy    chan sig
-	m          sync.Mutex
+	lock       sync.Mutex
 }
 
 func NewPool(size int) *Pool {
 	p := &Pool{
 		capacity:   int32(size),
-		freeSignal: make(chan sig, size),
+		freeSignal: make(chan sig, math.MaxInt32),
 		destroy:    make(chan sig, runtime.GOMAXPROCS(-1)),
 	}
 
@@ -68,8 +69,8 @@ func (p *Pool) Cap() int {
 }
 
 func (p *Pool) Destroy() error {
-	p.m.Lock()
-	defer p.m.Unlock()
+	p.lock.Lock()
+	defer p.lock.Unlock()
 	for i := 0; i < runtime.GOMAXPROCS(-1)+1; i++ {
 		p.destroy <- sig{}
 	}
@@ -82,50 +83,126 @@ func (p *Pool) reachLimit() bool {
 	return p.Running() >= p.Cap()
 }
 
-func (p *Pool) newWorker() *Worker {
-	var w *Worker
-	if p.reachLimit() {
-		<-p.freeSignal
-		return p.getWorker()
-	}
-	wp := p.workerPool.Get()
-	if wp == nil {
-		w = &Worker{
-			pool: p,
-			task: make(chan f),
-		}
-	} else {
-		w = wp.(*Worker)
-	}
-	w.run()
-	atomic.AddInt32(&p.running, 1)
-	return w
-}
+//func (p *Pool) newWorker() *Worker {
+//	var w *Worker
+//	if p.reachLimit() {
+//		<-p.freeSignal
+//		return p.getWorker()
+//	}
+//	wp := p.workerPool.Get()
+//	if wp == nil {
+//		w = &Worker{
+//			pool: p,
+//			task: make(chan f),
+//		}
+//	} else {
+//		w = wp.(*Worker)
+//	}
+//	w.run()
+//	atomic.AddInt32(&p.running, 1)
+//	return w
+//}
+//
+//func (p *Pool) getWorker() *Worker {
+//	var w *Worker
+//	p.lock.Lock()
+//	workers := p.workers
+//	n := len(workers) - 1
+//	if n < 0 {
+//		p.lock.Unlock()
+//		return p.newWorker()
+//	} else {
+//		w = workers[n]
+//		workers[n] = nil
+//		p.workers = workers[:n]
+//		//atomic.AddInt32(&p.running, 1)
+//	}
+//	p.lock.Unlock()
+//	return w
+//}
+
+//func (p *Pool) newWorker() *Worker {
+//	var w *Worker
+//	if p.reachLimit() {
+//		<-p.freeSignal
+//		return p.getWorker()
+//	}
+//	wp := p.workerPool.Get()
+//	if wp == nil {
+//		w = &Worker{
+//			pool: p,
+//			task: make(chan f),
+//		}
+//	} else {
+//		w = wp.(*Worker)
+//	}
+//	w.run()
+//	atomic.AddInt32(&p.running, 1)
+//	return w
+//}
 
 func (p *Pool) getWorker() *Worker {
+	//fmt.Printf("init running workers number:%d\n", p.running)
 	var w *Worker
-	p.m.Lock()
+	waiting := false
+
+	p.lock.Lock()
 	workers := p.workers
 	n := len(workers) - 1
 	if n < 0 {
-		p.m.Unlock()
-		return p.newWorker()
+		//fmt.Printf("running workers number:%d\n", p.running)
+		if p.running >= p.capacity {
+			waiting = true
+		}
 	} else {
 		w = workers[n]
 		workers[n] = nil
 		p.workers = workers[:n]
-		atomic.AddInt32(&p.running, 1)
+		//atomic.AddInt32(&p.running, 1)
+	}
+	p.lock.Unlock()
+
+	if waiting {
+		<-p.freeSignal
+		//p.lock.Lock()
+		//fmt.Println("wait for a worker")
+		//fmt.Println("get for a worker")
+		for {
+			p.lock.Lock()
+			workers = p.workers
+			l := len(workers) - 1
+			if l < 0 {
+				p.lock.Unlock()
+				continue
+			}
+			w = workers[l]
+			workers[l] = nil
+			p.workers = workers[:l]
+			p.lock.Unlock()
+			break
+		}
+		//p.lock.Unlock()
+	} else {
+		wp := p.workerPool.Get()
+		if wp == nil {
+			w = &Worker{
+				pool: p,
+				task: make(chan f),
+			}
+			w.run()
+			atomic.AddInt32(&p.running, 1)
+		} else {
+			w = wp.(*Worker)
+		}
 	}
-	p.m.Unlock()
 	return w
 }
 
 func (p *Pool) putWorker(worker *Worker) {
 	p.workerPool.Put(worker)
-	p.m.Lock()
+	p.lock.Lock()
 	p.workers = append(p.workers, worker)
-	if p.reachLimit() {
-		p.freeSignal <- sig{}
-	}
-	p.m.Unlock()
+	p.lock.Unlock()
+	p.freeSignal <- sig{}
+	//fmt.Printf("put a worker, running worker number:%d\n", p.Running())
 }