超大規模并發的場景下,不加限制的大規模的goroutine可能造成記憶體暴漲,給機器帶來極大的壓力,吞吐量下降和處理速度變慢。
而實作一個Goroutine Pool,複用goroutine,減輕runtime的排程壓力以及緩解記憶體壓力,依托這些優化,在大規模goroutine并發的場景下可以極大地提高并發性能。
Pool類型
type Pool struct {
// capacity of the pool.
//capacity是該Pool的容量,也就是開啟worker數量的上限,每一個worker需要一個goroutine去執行;
//worker類型為任務類。
capacity int32
// running is the number of the currently running goroutines.
//running是目前正在執行任務的worker數量
running int32
// expiryDuration set the expired time (second) of every worker.
//expiryDuration是worker的過期時長,在空閑隊列中的worker的最新一次運作時間與目前時間之差如果大于這個值則表示已過期,定時清理任務會清理掉這個worker;
expiryDuration time.Duration
// workers is a slice that store the available workers.
//任務隊列
workers []*Worker
// release is used to notice the pool to closed itself.
//當關閉該Pool支援通知所有worker退出運作以防goroutine洩露
release chan sig
// lock for synchronous operation
//用以支援Pool的同步操作
lock sync.Mutex
//once用在確定Pool關閉操作隻會執行一次
once sync.Once
}
初始化Pool
// NewPool generates a instance of ants pool
func NewPool(size, expiry int) (*Pool, error) {
if size <= 0 {
return nil, errors.New("Pool Size <0,not Create")
}
p := &Pool{
capacity: int32(size),
release: make(chan sig, 1),
expiryDuration: time.Duration(expiry) * time.Second,
running: 0,
}
// 啟動定期清理過期worker任務,獨立goroutine運作,
// 進一步節省系統資源
p.monitorAndClear()
return p, nil
}
擷取Worker
// getWorker returns a available worker to run the tasks.
func (p *Pool) getWorker() *Worker {
var w *Worker
// 标志,表示目前運作的worker數量是否已達容量上限
waiting := false
// 涉及從workers隊列取可用worker,需要加鎖
p.lock.Lock()
workers := p.workers
n := len(workers) - 1
fmt.Println("空閑worker數量:",n+1)
fmt.Println("協程池現在運作的worker數量:",p.running)
// 目前worker隊列為空(無空閑worker)
if n < 0 {
//沒有空閑的worker有兩種可能:
//1.運作的worker超出了pool容量
//2.目前是空pool,從未往pool添加任務或者一段時間内沒有任務添加,被定期清除
// 運作worker數目已達到該Pool的容量上限,置等待标志
if p.running >= p.capacity {
//print("超過上限")
waiting = true
} else {
// 目前無空閑worker但是Pool還沒有滿,
// 則可以直接新開一個worker執行任務
p.running++
w = &Worker{
pool: p,
task: make(chan functinType),
str:make(chan string),
}
}
// 有空閑worker,從隊列尾部取出一個使用
} else {
//<-p.freeSignal
w = workers[n]
workers[n] = nil
p.workers = workers[:n]
p.running++
}
// 判斷是否有worker可用結束,解鎖
p.lock.Unlock()
if waiting {
//當一個任務執行完以後會添加到池中,有了空閑的任務就可以繼續執行:
// 阻塞等待直到有空閑worker
for len(p.workers) == 0{
continue
}
p.lock.Lock()
workers = p.workers
l := len(workers) - 1
w = workers[l]
workers[l] = nil
p.workers = workers[:l]
p.running++
p.lock.Unlock()
}
return w
}
定期清理過期Worker
func (p *Pool) monitorAndClear() {
go func() {
for {
// 周期性循環檢查過期worker并清理
time.Sleep(p.expiryDuration)
currentTime := time.Now()
p.lock.Lock()
idleWorkers := p.workers
n := 0
for i, w := range idleWorkers {
// 計算目前時間減去該worker的最後運作時間之差是否符合過期時長
if currentTime.Sub(w.recycleTime) <= p.expiryDuration {
break
}
n = i
w.stop()
idleWorkers[i] = nil
}
if n > 0 {
n++
p.workers = idleWorkers[n:]
}
p.lock.Unlock()
}
}()
}
複用Worker
// putWorker puts a worker back into free pool, recycling the goroutines.
func (p *Pool) putWorker(worker *Worker) {
// 寫入回收時間,亦即該worker的最後運作時間
worker.recycleTime = time.Now()
p.lock.Lock()
p.running --
p.workers = append(p.workers, worker)
p.lock.Unlock()
}
動态擴容或者縮小容量
// ReSize change the capacity of this pool
func (p *Pool) ReSize(size int) {
cap := int(p.capacity)
if size < cap{
diff := cap - size
for i := 0; i < diff; i++ {
p.getWorker().stop()
}
} else if size == cap {
return
}
atomic.StoreInt32(&p.capacity, int32(size))
}
送出Worker
// Submit submit a task to pool
func (p *Pool) Submit(task functinType,str string) error {
if len(p.release) > 0 {
return errors.New("Pool is Close")
}
//建立或得到一個空閑的worker
w := p.getWorker()
w.run()
//将任務參數通過信道傳遞給它
w.sendarg(str)
//将任務通過信道傳遞給它
w.sendTask(task)
return nil
}
Worker類
package Poolpkg
import (
"sync/atomic"
"time"
)
type functinType func(string) error
// Worker is the actual executor who runs the tasks,
// it starts a goroutine that accepts tasks and
// performs function calls.
type Worker struct {
// pool who owns this worker.
pool *Pool
// task is a job should be done.
task chan functinType
// recycleTime will be update when putting a worker back into queue.
recycleTime time.Time
str chan string
}
// run starts a goroutine to repeat the process
// that performs the function calls.
func (w *Worker) run() {
go func() {
//監聽任務清單,一旦有任務立馬取出運作
count := 1
var str string
var f functinType
for count <=2{
select {
case str_temp, ok := <- w.str:
if !ok {
return
}
count ++
str = str_temp
case f_temp, ok := <-w.task:
if !ok {
//如果接收到關閉
atomic.AddInt32(&w.pool.running, -1)
close(w.task)
return
}
count ++
f = f_temp
}
}
err := f(str)
if err != nil{
//fmt.Println("執行任務失敗")
}
//回收複用
w.pool.putWorker(w)
return
}()
}
// stop this worker.
func (w *Worker) stop() {
w.sendTask(nil)
close(w.str)
}
// sendTask sends a task to this worker.
func (w *Worker) sendTask(task functinType) {
w.task <- task
}
func (w *Worker) sendarg(str string) {
w.str <- str
}
總結和實踐
怎麼了解Woreker,task、Pool的關系
Woker類型其實就是task的載體,Worker類型有兩個很重要的參數:
task chan functinType:用來是傳遞task。
str chan string:用來傳遞task所需的參數。
task是任務本身,它一般為一個函數,在程式中被定義為函數類型:
1
type functinType func(string) error
Pool存儲Worker,當使用者要執行一個task時,首先要得到一個Worker,必須從池中擷取,擷取到一個Worker後,就開啟一個協程去處理,在這個協程中接收任務task和參數。
//建立或得到一個空閑的worker
w := p.getWorker()<br>//開協程去處理
w.run()
//将任務參數通過信道傳遞給它
w.sendarg(str)
//将任務通過信道傳遞給它
w.sendTask(task)
Worker怎麼接收task和參數
1
count定義接收資料的個數,一個Woker必須接收到task和參數才能開始工作。<br>工作完後這個Worker被傳回到Pool中,下次還可以複用這個Worker,也就是複用Worker這個執行個體。
go func() {
//監聽任務清單,一旦有任務立馬取出運作
count := 1
var str string
var f functinType
for count <=2{
select {
case str_temp, ok := <- w.str:
if !ok {
return
}
count ++
str = str_temp
case f_temp, ok := <-w.task:
if !ok {
//如果接收到關閉
atomic.AddInt32(&w.pool.running, -1)
close(w.task)
return
}
count ++
f = f_temp
}
}
err := f(str)
if err != nil{
//fmt.Println("執行任務失敗")
}
//回收複用
w.pool.putWorker(w)
return
}()
Pool怎麼處理使用者送出task擷取Worker的請求
1.先得到Pool池中空閑Worker的數量,然後判斷
2.如果小于零,則表示池中沒有空閑的Worker,這裡有兩種原因:
- 1.運作的Worker數量超過了Pool容量,當使用者擷取Worker的請求數量激增,池中大多數Worker都是執行完任務的Worker重新添加到池中的,傳回的Worker跟不上激增的需求。
- 2.目前是空pool,從未往pool添加任務或者一段時間内沒有Worker任務運作,被定期清除。
3.如果大于或者等于零,有空閑的Worker直接從池中擷取最後一個Worker。
4.如果是第二種的第一種情況,則阻塞等待池中有空閑的Worker。
if waiting {
//當一個任務執行完以後會添加到池中,有了空閑的任務就可以繼續執行:
// 阻塞等待直到有空閑worker
for len(p.workers) == 0{
continue
}
p.lock.Lock()
workers = p.workers
l := len(workers) - 1
w = workers[l]
workers[l] = nil
p.workers = workers[:l]
p.running++
p.lock.Unlock()
}
5.如果是第二種的第二種情況,直接建立一個Worker執行個體。
// 目前無空閑worker但是Pool還沒有滿,
// 則可以直接新開一個worker執行任務
p.running++
w = &Worker{
pool: p,
task: make(chan functinType),
str:make(chan string),
}
測試
package main
import (
"Pool/Poolpkg"
"fmt"
)
func main(){<br> //開20個大小的Pool池,過期清除時間5分鐘
Pool,err := Poolpkg.NewPool(20,5)
i :=0
for i < 50 {
err = Pool.Submit(Print_Test1,"并發測試!")
if err != nil{
fmt.Println(err)
}
i++
}
}
源碼
Pool
package Poolpkg
import (
"errors"
"fmt"
"sync"
"sync/atomic"
"time"
)
type sig struct{}
// Pool accept the tasks from client,it limits the total
// of goroutines to a given number by recycling goroutines.
type Pool struct {
// capacity of the pool.
//capacity是該Pool的容量,也就是開啟worker數量的上限,每一個worker需要一個goroutine去執行;
//worker類型為任務類。
capacity int32
// running is the number of the currently running goroutines.
//running是目前正在執行任務的worker數量
running int32
// expiryDuration set the expired time (second) of every worker.
//expiryDuration是worker的過期時長,在空閑隊列中的worker的最新一次運作時間與目前時間之差如果大于這個值則表示已過期,定時清理任務會清理掉這個worker;
expiryDuration time.Duration
// workers is a slice that store the available workers.
//任務隊列
workers []*Worker
// release is used to notice the pool to closed itself.
//當關閉該Pool支援通知所有worker退出運作以防goroutine洩露
release chan sig
// lock for synchronous operation
//用以支援Pool的同步操作
lock sync.Mutex
//once用在確定Pool關閉操作隻會執行一次
once sync.Once
}
// NewPool generates a instance of ants pool
func NewPool(size, expiry int) (*Pool, error) {
if size <= 0 {
return nil, errors.New("Pool Size <0,not Create")
}
p := &Pool{
capacity: int32(size),
release: make(chan sig, 1),
expiryDuration: time.Duration(expiry) * time.Second,
running: 0,
}
// 啟動定期清理過期worker任務,獨立goroutine運作,
// 進一步節省系統資源
p.monitorAndClear()
return p, nil
}
// Submit submit a task to pool
func (p *Pool) Submit(task functinType,str string) error {
if len(p.release) > 0 {
return errors.New("Pool is Close")
}
//建立或得到一個空閑的worker
w := p.getWorker()
w.run()
//将任務參數通過信道傳遞給它
w.sendarg(str)
//将任務通過信道傳遞給它
w.sendTask(task)
return nil
}
// getWorker returns a available worker to run the tasks.
func (p *Pool) getWorker() *Worker {
var w *Worker
// 标志,表示目前運作的worker數量是否已達容量上限
waiting := false
// 涉及從workers隊列取可用worker,需要加鎖
p.lock.Lock()
workers := p.workers
n := len(workers) - 1
fmt.Println("空閑worker數量:",n+1)
fmt.Println("協程池現在運作的worker數量:",p.running)
// 目前worker隊列為空(無空閑worker)
if n < 0 {
//沒有空閑的worker有兩種可能:
//1.運作的worker超出了pool容量
//2.目前是空pool,從未往pool添加任務或者一段時間内沒有任務添加,被定期清除
// 運作worker數目已達到該Pool的容量上限,置等待标志
if p.running >= p.capacity {
//print("超過上限")
waiting = true
} else {
// 目前無空閑worker但是Pool還沒有滿,
// 則可以直接新開一個worker執行任務
p.running++
w = &Worker{
pool: p,
task: make(chan functinType),
str:make(chan string),
}
}
// 有空閑worker,從隊列尾部取出一個使用
} else {
//<-p.freeSignal
w = workers[n]
workers[n] = nil
p.workers = workers[:n]
p.running++
}
// 判斷是否有worker可用結束,解鎖
p.lock.Unlock()
if waiting {
//當一個任務執行完以後會添加到池中,有了空閑的任務就可以繼續執行:
// 阻塞等待直到有空閑worker
for len(p.workers) == 0{
continue
}
p.lock.Lock()
workers = p.workers
l := len(workers) - 1
w = workers[l]
workers[l] = nil
p.workers = workers[:l]
p.running++
p.lock.Unlock()
}
return w
}
//定期清理過期Worker
func (p *Pool) monitorAndClear() {
go func() {
for {
// 周期性循環檢查過期worker并清理
time.Sleep(p.expiryDuration)
currentTime := time.Now()
p.lock.Lock()
idleWorkers := p.workers
n := 0
for i, w := range idleWorkers {
// 計算目前時間減去該worker的最後運作時間之差是否符合過期時長
if currentTime.Sub(w.recycleTime) <= p.expiryDuration {
break
}
n = i
w.stop()
idleWorkers[i] = nil
p.running--
}
if n > 0 {
n++
p.workers = idleWorkers[n:]
}
p.lock.Unlock()
}
}()
}
//Worker回收(goroutine複用)
// putWorker puts a worker back into free pool, recycling the goroutines.
func (p *Pool) putWorker(worker *Worker) {
// 寫入回收時間,亦即該worker的最後運作時間
worker.recycleTime = time.Now()
p.lock.Lock()
p.running --
p.workers = append(p.workers, worker)
p.lock.Unlock()
}
//動态擴容或者縮小池容量
// ReSize change the capacity of this pool
func (p *Pool) ReSize(size int) {
cap := int(p.capacity)
if size < cap{
diff := cap - size
for i := 0; i < diff; i++ {
p.getWorker().stop()
}
} else if size == cap {
return
}
atomic.StoreInt32(&p.capacity, int32(size))
Woker
package Poolpkg
import (
"sync/atomic"
"time"
)
type functinType func(string) error
// Worker is the actual executor who runs the tasks,
// it starts a goroutine that accepts tasks and
// performs function calls.
type Worker struct {
// pool who owns this worker.
pool *Pool
// task is a job should be done.
task chan functinType
// recycleTime will be update when putting a worker back into queue.
recycleTime time.Time
str chan string
}
// run starts a goroutine to repeat the process
// that performs the function calls.
func (w *Worker) run() {
go func() {
//監聽任務清單,一旦有任務立馬取出運作
count := 1
var str string
var f functinType
for count <=2{
select {
case str_temp, ok := <- w.str:
if !ok {
return
}
count ++
str = str_temp
case f_temp, ok := <-w.task:
if !ok {
//如果接收到關閉
atomic.AddInt32(&w.pool.running, -1)
close(w.task)
return
}
count ++
f = f_temp
}
}
err := f(str)
if err != nil{
//fmt.Println("執行任務失敗")
}
//回收複用
w.pool.putWorker(w)
return
}()
}
// stop this worker.
func (w *Worker) stop() {
w.sendTask(nil)
close(w.str)
}
// sendTask sends a task to this worker.
func (w *Worker) sendTask(task functinType) {
w.task <- task
}
func (w *Worker) sendarg(str string) {
w.str <- str
}