ants/README.md

<p align="center">
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<b>A goroutine pool for Go</b>
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English | [中文](README_ZH.md)

## 📖 Introduction

Library `ants` implements a goroutine pool with fixed capacity, managing and recycling a massive number of goroutines, allowing developers to limit the number of goroutines in your concurrent programs.

## 🚀 Features:

- Managing and recycling a massive number of goroutines automatically
- Purging overdue goroutines periodically
- Abundant APIs: submitting tasks, getting the number of running goroutines, tuning the capacity of the pool dynamically, releasing the pool, rebooting the pool
- Handle panic gracefully to prevent programs from crash
- Efficient in memory usage and it even achieves [higher performance](#-performance-summary) than unlimited goroutines in Golang
- Nonblocking mechanism

## 💡 How `ants` works

### Flow Diagram

<p align="center">
<img width="1011" alt="ants-flowchart-en" src="https://user-images.githubusercontent.com/7496278/66396509-7b42e700-ea0c-11e9-8612-b71a4b734683.png">
</p>

### Activity Diagrams

![](https://raw.githubusercontent.com/panjf2000/illustrations/master/go/ants-pool-1.png)

![](https://raw.githubusercontent.com/panjf2000/illustrations/master/go/ants-pool-2.png)

![](https://raw.githubusercontent.com/panjf2000/illustrations/master/go/ants-pool-3.png)

![](https://raw.githubusercontent.com/panjf2000/illustrations/master/go/ants-pool-4.png)

## 🧰 How to install

### For `ants` v1

``` powershell
go get -u github.com/panjf2000/ants
```

### For `ants` v2 (with GO111MODULE=on)

```powershell
go get -u github.com/panjf2000/ants/v2
```

## 🛠 How to use
Just imagine that your program starts a massive number of goroutines, resulting in a huge consumption of memory. To mitigate that kind of situation, all you need to do is to import `ants` package and submit all your tasks to a default pool with fixed capacity, activated when package `ants` is imported:

``` go
package main

import (
	"fmt"
	"sync"
	"sync/atomic"
	"time"

	"github.com/panjf2000/ants/v2"
)

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

	// Use the common pool.
	var wg sync.WaitGroup
	syncCalculateSum := func() {
		demoFunc()
		wg.Done()
	}
	for i := 0; i < runTimes; i++ {
		wg.Add(1)
		_ = ants.Submit(syncCalculateSum)
	}
	wg.Wait()
	fmt.Printf("running goroutines: %d\n", ants.Running())
	fmt.Printf("finish all tasks.\n")

	// Use the pool with a function,
	// set 10 to the capacity of goroutine pool and 1 second for expired duration.
	p, _ := ants.NewPoolWithFunc(10, func(i interface{}) {
		myFunc(i)
		wg.Done()
	})
	defer p.Release()
	// Submit tasks one by one.
	for i := 0; i < runTimes; i++ {
		wg.Add(1)
		_ = p.Invoke(int32(i))
	}
	wg.Wait()
	fmt.Printf("running goroutines: %d\n", p.Running())
	fmt.Printf("finish all tasks, result is %d\n", sum)
	if sum != 499500 {
		panic("the final result is wrong!!!")
	}

	// Use the MultiPool and set the capacity of the 10 goroutine pools to unlimited.
	// If you use -1 as the pool size parameter, the size will be unlimited.
	// There are two load-balancing algorithms for pools: ants.RoundRobin and ants.LeastTasks.
	mp, _ := ants.NewMultiPool(10, -1, ants.RoundRobin)
	defer mp.ReleaseTimeout(5 * time.Second)
	for i := 0; i < runTimes; i++ {
		wg.Add(1)
		_ = mp.Submit(syncCalculateSum)
	}
	wg.Wait()
	fmt.Printf("running goroutines: %d\n", mp.Running())
	fmt.Printf("finish all tasks.\n")

	// Use the MultiPoolFunc and set the capacity of 10 goroutine pools to (runTimes/10).
	mpf, _ := ants.NewMultiPoolWithFunc(10, runTimes/10, func(i interface{}) {
		myFunc(i)
		wg.Done()
	}, ants.LeastTasks)
	defer mpf.ReleaseTimeout(5 * time.Second)
	for i := 0; i < runTimes; i++ {
		wg.Add(1)
		_ = mpf.Invoke(int32(i))
	}
	wg.Wait()
	fmt.Printf("running goroutines: %d\n", mpf.Running())
	fmt.Printf("finish all tasks, result is %d\n", sum)
	if sum != 499500*2 {
		panic("the final result is wrong!!!")
	}
}
```

###  Functional options for ants pool

```go
// Option represents the optional function.
type Option func(opts *Options)

// Options contains all options which will be applied when instantiating a ants pool.
type Options struct {
	// ExpiryDuration is a period for the scavenger goroutine to clean up those expired workers,
	// the scavenger scans all workers every `ExpiryDuration` and clean up those workers that haven't been
	// used for more than `ExpiryDuration`.
	ExpiryDuration time.Duration

	// PreAlloc indicates whether to make memory pre-allocation when initializing Pool.
	PreAlloc bool

	// Max number of goroutine blocking on pool.Submit.
	// 0 (default value) means no such limit.
	MaxBlockingTasks int

	// When Nonblocking is true, Pool.Submit will never be blocked.
	// ErrPoolOverload will be returned when Pool.Submit cannot be done at once.
	// When Nonblocking is true, MaxBlockingTasks is inoperative.
	Nonblocking bool

	// PanicHandler is used to handle panics from each worker goroutine.
	// if nil, panics will be thrown out again from worker goroutines.
	PanicHandler func(interface{})

	// Logger is the customized logger for logging info, if it is not set,
	// default standard logger from log package is used.
	Logger Logger
}

// WithOptions accepts the whole options config.
func WithOptions(options Options) Option {
	return func(opts *Options) {
		*opts = options
	}
}

// WithExpiryDuration sets up the interval time of cleaning up goroutines.
func WithExpiryDuration(expiryDuration time.Duration) Option {
	return func(opts *Options) {
		opts.ExpiryDuration = expiryDuration
	}
}

// WithPreAlloc indicates whether it should malloc for workers.
func WithPreAlloc(preAlloc bool) Option {
	return func(opts *Options) {
		opts.PreAlloc = preAlloc
	}
}

// WithMaxBlockingTasks sets up the maximum number of goroutines that are blocked when it reaches the capacity of pool.
func WithMaxBlockingTasks(maxBlockingTasks int) Option {
	return func(opts *Options) {
		opts.MaxBlockingTasks = maxBlockingTasks
	}
}

// WithNonblocking indicates that pool will return nil when there is no available workers.
func WithNonblocking(nonblocking bool) Option {
	return func(opts *Options) {
		opts.Nonblocking = nonblocking
	}
}

// WithPanicHandler sets up panic handler.
func WithPanicHandler(panicHandler func(interface{})) Option {
	return func(opts *Options) {
		opts.PanicHandler = panicHandler
	}
}

// WithLogger sets up a customized logger.
func WithLogger(logger Logger) Option {
	return func(opts *Options) {
		opts.Logger = logger
	}
}
```

`ants.Options`contains all optional configurations of the ants pool, which allows you to customize the goroutine pool by invoking option functions to set up each configuration in `NewPool`/`NewPoolWithFunc`method.

### Customize limited pool

`ants` also supports customizing the capacity of the pool. You can invoke the `NewPool` method to instantiate a pool with a given capacity, as follows:

``` go
p, _ := ants.NewPool(10000)
```

### Submit tasks
Tasks can be submitted by calling `ants.Submit(func())`
```go
ants.Submit(func(){})
```

### Tune pool capacity in runtime
You can tune the capacity of  `ants` pool in runtime with `Tune(int)`:

``` go
pool.Tune(1000) // Tune its capacity to 1000
pool.Tune(100000) // Tune its capacity to 100000
```

Don't worry about the contention problems in this case, the method here is thread-safe (or should be called goroutine-safe).

### Pre-malloc goroutine queue in pool

`ants` allows you to pre-allocate the memory of the goroutine queue in the pool, which may get a performance enhancement under some special certain circumstances such as the scenario that requires a pool with ultra-large capacity, meanwhile, each task in goroutine lasts for a long time, in this case, pre-mallocing will reduce a lot of memory allocation in goroutine queue.

```go
// ants will pre-malloc the whole capacity of pool when you invoke this method
p, _ := ants.NewPool(100000, ants.WithPreAlloc(true))
```

### Release Pool

```go
pool.Release()
```

### Reboot Pool

```go
// A pool that has been released can be still used once you invoke the Reboot().
pool.Reboot()
```

## ⚙️ About sequence

All tasks submitted to `ants` pool will not be guaranteed to be addressed in order, because those tasks scatter among a series of concurrent workers, thus those tasks would be executed concurrently.

## 👏 Contributors

Please read our [Contributing Guidelines](CONTRIBUTING.md) before opening a PR and thank you to all the developers who already made contributions to `ants`!

<a href="https://github.com/panjf2000/ants/graphs/contributors">
  <img src="https://contrib.rocks/image?repo=panjf2000/ants" />
</a>

## 📄 License

The source code in `ants` is available under the [MIT License](/LICENSE).

## 📚 Relevant Articles

-  [Goroutine 并发调度模型深度解析之手撸一个高性能 goroutine 池](https://taohuawu.club/high-performance-implementation-of-goroutine-pool)
-  [Visually Understanding Worker Pool](https://medium.com/coinmonks/visually-understanding-worker-pool-48a83b7fc1f5)
-  [The Case For A Go Worker Pool](https://brandur.org/go-worker-pool)
-  [Go Concurrency - GoRoutines, Worker Pools and Throttling Made Simple](https://twin.sh/articles/39/go-concurrency-goroutines-worker-pools-and-throttling-made-simple)

## 🖥 Use cases

### business corporations

Trusted by the following corporations/organizations.

<table>
  <tbody>
    <tr>
      <td align="center" valign="middle">
        <a href="https://www.tencent.com/">
          <img src="https://res.strikefreedom.top/static_res/logos/tencent_logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.bytedance.com/en/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/ByteDance_Logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://tieba.baidu.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/baidu-tieba-logo.png" width="300" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://weibo.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/weibo-logo.png" width="300" />
        </a>
      </td>
    </tr>
    <tr>
      <td align="center" valign="middle">
        <a href="https://www.tencentmusic.com/en-us/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/tencent-music-logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.futuhk.com/en/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/futu-logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.shopify.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/shopify-logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.wechat.com/en/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/wechat-logo.png" width="250" />
        </a>
      </td>
    </tr>
    <tr>
      <td align="center" valign="middle">
        <a href="https://www.baidu.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/baidu-mobile-logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.360.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/360-logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.huaweicloud.com/intl/en-us/" target="_blank">
          <img src="https://res-static.hc-cdn.cn/cloudbu-site/china/zh-cn/%E7%BB%84%E4%BB%B6%E9%AA%8C%E8%AF%81/pep-common-header/logo-en.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.matrixorigin.io/" target="_blank">
          <img src="https://www.matrixorigin.io/_next/static/media/logo-light-en.42553c69.svg" width="250" />
        </a>
      </td>
    </tr>
    <tr>
      <td align="center" valign="middle">
        <a href="https://adguard-dns.io/" target="_blank">
          <img src="https://cdn.adtidy.org/website/images/AdGuardDNS_black.svg" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://bk.tencent.com/" target="_blank">
          <img src="https://static.apiseven.com/2022/11/14/6371adab14119.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.alibabacloud.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/aliyun-intl-logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://www.zuoyebang.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/zuoyebang-logo.jpeg" width="300" />
        </a>
      </td>
    </tr>
    <tr>
      <td align="center" valign="middle">
        <a href="https://www.antgroup.com/en/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/ant-group-logo.png" width="250" />
        </a>
      </td>
      <td align="center" valign="middle">
        <a href="https://zilliz.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/zilliz-logo.png" width="250" />
        </a>
      </td>
      </td>
      <td align="center" valign="middle">
        <a href="https://amap.com/" target="_blank">
          <img src="https://res.strikefreedom.top/static_res/logos/amap-logo.png" width="250" />
        </a>
      </td>
    </tr>
  </tbody>
</table>

If you're also using `ants` in production, please help us enrich this list by opening a pull request.

### open-source software

The open-source projects below do concurrent programming with the help of `ants`.

- [gnet](https://github.com/panjf2000/gnet):  A high-performance, lightweight, non-blocking, event-driven networking framework written in pure Go.
- [milvus](https://github.com/milvus-io/milvus): An open-source vector database for scalable similarity search and AI applications.
- [nps](https://github.com/ehang-io/nps): A lightweight, high-performance, powerful intranet penetration proxy server, with a powerful web management terminal.
- [siyuan](https://github.com/siyuan-note/siyuan): SiYuan is a local-first personal knowledge management system that supports complete offline use, as well as end-to-end encrypted synchronization.
- [osmedeus](https://github.com/j3ssie/osmedeus): A Workflow Engine for Offensive Security.
- [jitsu](https://github.com/jitsucom/jitsu/tree/master): An open-source Segment alternative. Fully-scriptable data ingestion engine for modern data teams. Set-up a real-time data pipeline in minutes, not days.
- [triangula](https://github.com/RH12503/triangula): Generate high-quality triangulated and polygonal art from images.
- [teler](https://github.com/kitabisa/teler): Real-time HTTP Intrusion Detection.
- [bsc](https://github.com/binance-chain/bsc): A Binance Smart Chain client based on the go-ethereum fork.
- [jaeles](https://github.com/jaeles-project/jaeles): The Swiss Army knife for automated Web Application Testing.
- [devlake](https://github.com/apache/incubator-devlake): The open-source dev data platform & dashboard for your DevOps tools.
- [matrixone](https://github.com/matrixorigin/matrixone): MatrixOne is a future-oriented hyper-converged cloud and edge native DBMS that supports transactional, analytical, and streaming workloads with a simplified and distributed database engine, across multiple data centers, clouds, edges and other heterogeneous infrastructures.
- [bk-bcs](https://github.com/TencentBlueKing/bk-bcs): BlueKing Container Service (BCS, same below) is a container management and orchestration platform for the micro-services under the BlueKing ecosystem.
- [trueblocks-core](https://github.com/TrueBlocks/trueblocks-core): TrueBlocks improves access to blockchain data for any EVM-compatible chain (particularly Ethereum mainnet) while remaining entirely local.
- [openGemini](https://github.com/openGemini/openGemini): openGemini is an open-source,cloud-native time-series database(TSDB) that can be widely used in IoT, Internet of Vehicles(IoV), O&M monitoring, and industrial Internet scenarios.
- [AdGuardDNS](https://github.com/AdguardTeam/AdGuardDNS): AdGuard DNS is an alternative solution for tracker blocking, privacy protection, and parental control.
- [WatchAD2.0](https://github.com/Qihoo360/WatchAD2.0): WatchAD2.0 是 360 信息安全中心开发的一款针对域安全的日志分析与监控系统，它可以收集所有域控上的事件日志、网络流量，通过特征匹配、协议分析、历史行为、敏感操作和蜜罐账户等方式来检测各种已知与未知威胁，功能覆盖了大部分目前的常见内网域渗透手法。
- [vanus](https://github.com/vanus-labs/vanus): Vanus is a Serverless, event streaming system with processing capabilities. It easily connects SaaS, Cloud Services, and Databases to help users build next-gen Event-driven Applications.
- [trpc-go](https://github.com/trpc-group/trpc-go): A pluggable, high-performance RPC framework written in Golang.
- [motan-go](https://github.com/weibocom/motan-go): a remote procedure call (RPC) framework for the rapid development of high-performance distributed services.

#### All use cases:

- [Repositories that depend on ants/v2](https://github.com/panjf2000/ants/network/dependents?package_id=UGFja2FnZS0yMjY2ODgxMjg2)

- [Repositories that depend on ants/v1](https://github.com/panjf2000/ants/network/dependents?package_id=UGFja2FnZS0yMjY0ODMzNjEw)

If you have `ants` integrated into projects, feel free to open a pull request refreshing this list of use cases.

## 🔋 JetBrains OS licenses

`ants` has been being developed with GoLand under the **free JetBrains Open Source license(s)** granted by JetBrains s.r.o., hence I would like to express my thanks here.

<a href="https://www.jetbrains.com/?from=ants" target="_blank"><img src="https://resources.jetbrains.com/storage/products/company/brand/logos/jetbrains.svg" alt="JetBrains logo."></a>

## 💰 Backers

Support us with a monthly donation and help us continue our activities.

<a href="https://opencollective.com/ants#backers" target="_blank"><img src="https://opencollective.com/ants/backers.svg"></a>

## 💎 Sponsors

Become a bronze sponsor with a monthly donation of $10 and get your logo on our README on GitHub.

<a href="https://opencollective.com/ants#sponsors" target="_blank"><img src="https://opencollective.com/ants/sponsors.svg"></a>

## ☕️ Buy me a coffee

> Please be sure to leave your name, GitHub account, or other social media accounts when you donate by the following means so that I can add it to the list of donors as a token of my appreciation.

<img src="https://raw.githubusercontent.com/panjf2000/illustrations/master/payments/WeChatPay.JPG" width="250" align="middle"/>&nbsp;&nbsp;
<img src="https://raw.githubusercontent.com/panjf2000/illustrations/master/payments/AliPay.JPG" width="250" align="middle"/>&nbsp;&nbsp;
<a href="https://www.paypal.me/R136a1X" target="_blank"><img src="https://raw.githubusercontent.com/panjf2000/illustrations/master/payments/PayPal.JPG" width="250" align="middle"/></a>&nbsp;&nbsp;

## 🔋 Sponsorship

<p>
  <a href="https://www.digitalocean.com/">
    <img src="https://opensource.nyc3.cdn.digitaloceanspaces.com/attribution/assets/PoweredByDO/DO_Powered_by_Badge_blue.svg" width="201px">
  </a>
</p>