ants/README.md

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# ants
<div align="center"><img src="ants_logo.png"/></div>
<p align="center">A goroutine pool for Go</p>
[![Build Status][1]][2]
[![codecov][3]][4]
[![goreportcard for panjf2000/ants][5]][6]
[![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/goroutine-pool)
Package `ants` implements a fixed goroutine pool for managing and recycling a massive number of goroutines, allowing developers to limit the number of goroutines that created in your concurrent programs.
## Features:
- Automatically managing and recycling a massive number of goroutines.
- Periodically clearing overdue goroutines.
- Friendly interfaces: submitting tasks, getting the number of running goroutines, readjusting capacity of pool dynamically, closing pool.
- Efficient in memory usage and it even achieves higher performance than unlimited goroutines in golang.
## How to install
``` sh
go get -u github.com/panjf2000/ants
```
Or, using glide:
``` sh
glide get github.com/panjf2000/ants
```
## How to use
If your program will generate a massive number of goroutines and you don't want them to consume a vast amount of memory, with `ants`, all you need to do is to import `ants` package and submit all your tasks to the default limited pool created when `ants` was imported:
``` go
package main
import (
"fmt"
"sync"
"sync/atomic"
"time"
"github.com/panjf2000/ants"
)
var sum int32
func myFunc(i interface{}) {
n := i.(int32)
atomic.AddInt32(&sum, n)
fmt.Printf("run with %d\n", n)
}
func demoFunc() {
time.Sleep(10 * time.Millisecond)
fmt.Println("Hello World!")
}
func main() {
defer ants.Release()
runTimes := 1000
// Uses the common pool
var wg sync.WaitGroup
for i := 0; i < runTimes; i++ {
wg.Add(1)
ants.Submit(func() {
demoFunc()
wg.Done()
})
}
wg.Wait()
fmt.Printf("running goroutines: %d\n", ants.Running())
fmt.Printf("finish all tasks.\n")
// Uses the pool with a function,
// sets 10 to the size of goroutine pool and 1 second for expired duration
p, _ := ants.NewPoolWithFunc(10, func(i interface{}) {
myFunc(i)
wg.Done()
})
defer p.Release()
// Submits tasks
for i := 0; i < runTimes; i++ {
wg.Add(1)
p.Serve(int32(i))
}
wg.Wait()
fmt.Printf("running goroutines: %d\n", p.Running())
fmt.Printf("finish all tasks, result is %d\n", sum)
}
```
## Integrate with http server
```go
package main
import (
"io/ioutil"
"net/http"
"github.com/panjf2000/ants"
)
type Request struct {
Param []byte
Result chan []byte
}
func main() {
pool, _ := ants.NewPoolWithFunc(100, func(payload interface{}) {
request, ok := payload.(*Request)
if !ok {
return
}
reverseParam := func(s []byte) []byte {
for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
s[i], s[j] = s[j], s[i]
}
return s
}(request.Param)
request.Result <- reverseParam
})
defer pool.Release()
http.HandleFunc("/reverse", func(w http.ResponseWriter, r *http.Request) {
param, err := ioutil.ReadAll(r.Body)
if err != nil {
http.Error(w, "request error", http.StatusInternalServerError)
}
defer r.Body.Close()
request := &Request{Param: param, Result: make(chan []byte)}
// Throttles the requests with ants pool. This process is asynchronous and
// you can receive a result from the channel defined outside.
if err := pool.Serve(request); err != nil {
http.Error(w, "throttle limit error", http.StatusInternalServerError)
}
w.Write(<-request.Result)
})
http.ListenAndServe(":8080", nil)
}
```
## Submits tasks
Tasks can be submitted by calling `ants.Submit(func())`
```go
ants.Submit(func(){})
```
## Customizes limited pool
`ants` also supports customizing limited pool. You can use the `NewPool` method to create a pool with the given capacity, as following:
``` go
// Sets 10000 the size of goroutine pool
p, _ := ants.NewPool(10000)
// Submits a task
p.Submit(func(){})
```
## Tuning pool capacity
You can change `ants` pool capacity at any time with `ReSize(int)`:
``` go
pool.ReSize(1000) // Tunes its capacity to 1000
pool.ReSize(100000) // Tunes its capacity to 100000
```
Don't worry about the synchronous problems in this case, this method is thread-safe.
## About sequence
All the tasks submitted to `ants` pool will not be guaranteed to be processed in order, because those tasks distribute among a series of concurrent workers, thus those tasks are processed concurrently.
## Benchmarks
```
OS : macOS High Sierra
Processor : 2.7 GHz Intel Core i5
Memory : 8 GB 1867 MHz DDR3
Go1.9
```
<div align="center"><img src="ants_benchmarks.png"/></div>
In that benchmark-picture, the first and second benchmarks performed test with 1M tasks and the rest of benchmarks performed test with 10M tasks, both unlimited goroutines and `ants` pool, and the capacity of this `ants` goroutine-pool was limited to 50K.
- BenchmarkGoroutine-4 represents the benchmarks with unlimited goroutines in golang.
- BenchmarkPoolGroutine-4 represents the benchmarks with a `ants` pool.
The test data above is a basic benchmark and the more detailed benchmarks will be uploaded later.
### Benchmarks with Pool
![](benchmark_pool.png)
In that benchmark-picture, the first and second benchmarks performed test with 1M tasks and the rest of benchmarks performed test with 10M tasks, both unlimited goroutines and `ants` pool, and the capacity of this `ants` goroutine-pool was limited to 50K.
**As you can see, `ants` can up to 2x faster than goroutines without pool (10M tasks) and it only consumes half memory comparing with goroutines without pool. (both 1M and 10M tasks)**
### Benchmarks with PoolWithFunc
![](ants_bench_poolwithfunc.png)
### Throughput (it is suitable for scenarios where asynchronous tasks are submitted without concern for results)
#### 100K tasks
![](ants_bench_10w.png)
#### 1M tasks
![](ants_bench_100w.png)
#### 10M tasks
![](ants_bench_1000w.png)
There was only the test of `ants` Pool because my computer was crash when it reached 10M goroutines without pool.
**In conclusion, `ants` can up to 2x~6x faster than goroutines without pool and the memory consumption is reduced by 10 to 20 times.**
[1]: https://travis-ci.com/panjf2000/ants.svg?branch=master
[2]: https://travis-ci.com/panjf2000/ants
[3]: https://codecov.io/gh/panjf2000/ants/branch/master/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://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