ants

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Published: May 11, 2020 License: MIT Imports: 9 Imported by: 1,061

README

A goroutine pool in Go


English | 🇨🇳中文

📖 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 capacity of pool dynamically, releasing pool, rebooting pool
  • Handle panic gracefully to prevent programs from crash
  • Efficient in memory usage and it even achieves higher performance than unlimited goroutines in Golang
  • Nonblocking mechanism

⚔️ Tested in the following Golang versions:

  • 1.8.x
  • 1.9.x
  • 1.10.x
  • 1.11.x
  • 1.12.x
  • 1.13.x

💡 ants works as the flowing flowchart

ants-flowchart-en

🧰 How to install

For ants v1

go get -u github.com/panjf2000/ants

For ants v2 (with GO111MODULE=on)

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

🛠 How to use

Just take a imagination 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:

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)
}

Integrate with http server

package main

import (
	"io/ioutil"
	"net/http"

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

type Request struct {
	Param  []byte
	Result chan []byte
}

func main() {
	pool, _ := ants.NewPoolWithFunc(100000, 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)}

		// Throttle the requests traffic with ants pool. This process is asynchronous and
		// you can receive a result from the channel defined outside.
		if err := pool.Invoke(request); err != nil {
			http.Error(w, "throttle limit error", http.StatusInternalServerError)
		}

		w.Write(<-request.Result)
	})

	http.ListenAndServe(":8080", nil)
}

Functional options for ants pool

// 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 sets the expired time (second) of every worker.
	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{})
}

// 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
	}
}

ants.Optionscontains all optional configurations of ants pool, which allows you to customize the goroutine pool by invoking option functions to set up each configuration in NewPool/NewPoolWithFuncmethod.

Customize limited pool

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

// Set 10000 the size of goroutine pool
p, _ := ants.NewPool(10000)

Submit tasks

Tasks can be submitted by calling ants.Submit(func())

ants.Submit(func(){})

Tune pool capacity in runtime

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

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

Don't worry about the synchronous 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 memory of goroutine queue in 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.

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

Release Pool

pool.Release()

Reboot Pool

// 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.

🧲 Benchmarks

In this benchmark result, the first and second benchmarks performed test cases with 1M tasks and the rest of benchmarks performed test cases with 10M tasks, both in 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.

Benchmarks with Pool

In above benchmark result, the first and second benchmarks performed test cases with 1M tasks and the rest of benchmarks performed test cases with 10M tasks, both in unlimited goroutines and ants pool, and the capacity of this ants goroutine-pool was limited to 50K.

As you can see, ants performs 2 times faster than goroutines without pool (10M tasks) and it only consumes half the memory comparing with goroutines without pool. (both in 1M and 10M tasks)

Benchmarks with PoolWithFunc

Throughput (it is suitable for scenarios where tasks are submitted asynchronously without waiting for the final results)

100K tasks

1M tasks

10M tasks

📊 Performance Summary

In conclusion, ants performs 2~6 times faster than goroutines without a pool and the memory consumption is reduced by 10 to 20 times.

👏 Contributors

Please read our Contributing Guidelines before opening a PR and thank you to all the developers who already made contributions to ants!

📄 License

Source code in ants is available under the MIT License.

📚 Relevant Articles

👨‍👨‍👧‍👦 Users of ants (please feel free to add your projects here ~~)

     

JetBrains OS licenses

ants had 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.

💰 Backers

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

💎 Sponsors

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

☕️ Buy me a coffee

        

Documentation

Index

Constants

View Source
const (
	// DefaultAntsPoolSize is the default capacity for a default goroutine pool.
	DefaultAntsPoolSize = math.MaxInt32

	// DefaultCleanIntervalTime is the interval time to clean up goroutines.
	DefaultCleanIntervalTime = time.Second
)
View Source
const (
	// OPENED represents that the pool is opened.
	OPENED = iota

	// CLOSED represents that the pool is closed.
	CLOSED
)

Variables

View Source
var (

	// ErrInvalidPoolSize will be returned when setting a negative number as pool capacity.
	ErrInvalidPoolSize = errors.New("invalid size for pool")

	// ErrLackPoolFunc will be returned when invokers don't provide function for pool.
	ErrLackPoolFunc = errors.New("must provide function for pool")

	// ErrInvalidPoolExpiry will be returned when setting a negative number as the periodic duration to purge goroutines.
	ErrInvalidPoolExpiry = errors.New("invalid expiry for pool")

	// ErrPoolClosed will be returned when submitting task to a closed pool.
	ErrPoolClosed = errors.New("this pool has been closed")

	// ErrPoolOverload will be returned when the pool is full and no workers available.
	ErrPoolOverload = errors.New("too many goroutines blocked on submit or Nonblocking is set")
)

Functions

func Cap

func Cap() int

Cap returns the capacity of this default pool.

func Free

func Free() int

Free returns the available goroutines to work.

func Reboot added in v2.3.0

func Reboot()

Reboot reboots the default pool.

func Release

func Release()

Release Closes the default pool.

func Running

func Running() int

Running returns the number of the currently running goroutines.

func Submit

func Submit(task func()) error

Submit submits a task to pool.

Types

type Logger added in v2.4.0

type Logger interface {
	// Printf must have the same semantics as log.Printf.
	Printf(format string, args ...interface{})
}

Logger is used for logging formatted messages.

type Option

type Option func(opts *Options)

Option represents the optional function.

func WithExpiryDuration

func WithExpiryDuration(expiryDuration time.Duration) Option

WithExpiryDuration sets up the interval time of cleaning up goroutines.

func WithLogger added in v2.4.0

func WithLogger(logger Logger) Option

WithLogger sets up a customized logger.

func WithMaxBlockingTasks

func WithMaxBlockingTasks(maxBlockingTasks int) Option

WithMaxBlockingTasks sets up the maximum number of goroutines that are blocked when it reaches the capacity of pool.

func WithNonblocking

func WithNonblocking(nonblocking bool) Option

WithNonblocking indicates that pool will return nil when there is no available workers.

func WithOptions

func WithOptions(options Options) Option

WithOptions accepts the whole options config.

func WithPanicHandler

func WithPanicHandler(panicHandler func(interface{})) Option

WithPanicHandler sets up panic handler.

func WithPreAlloc

func WithPreAlloc(preAlloc bool) Option

WithPreAlloc indicates whether it should malloc for workers.

type Options

type Options struct {
	// ExpiryDuration sets the expired time of every worker.
	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
}

Options contains all options which will be applied when instantiating a ants pool.

type Pool

type Pool struct {
	// contains filtered or unexported fields
}

Pool accepts the tasks from client, it limits the total of goroutines to a given number by recycling goroutines.

func NewPool

func NewPool(size int, options ...Option) (*Pool, error)

NewPool generates an instance of ants pool.

func (*Pool) Cap

func (p *Pool) Cap() int

Cap returns the capacity of this pool.

func (*Pool) Free

func (p *Pool) Free() int

Free returns the available goroutines to work.

func (*Pool) Reboot added in v2.3.0

func (p *Pool) Reboot()

Reboot reboots a released pool.

func (*Pool) Release

func (p *Pool) Release()

Release Closes this pool.

func (*Pool) Running

func (p *Pool) Running() int

Running returns the number of the currently running goroutines.

func (*Pool) Submit

func (p *Pool) Submit(task func()) error

Submit submits a task to this pool.

func (*Pool) Tune

func (p *Pool) Tune(size int)

Tune changes the capacity of this pool.

type PoolWithFunc

type PoolWithFunc struct {
	// contains filtered or unexported fields
}

PoolWithFunc accepts the tasks from client, it limits the total of goroutines to a given number by recycling goroutines.

func NewPoolWithFunc

func NewPoolWithFunc(size int, pf func(interface{}), options ...Option) (*PoolWithFunc, error)

NewPoolWithFunc generates an instance of ants pool with a specific function.

func (*PoolWithFunc) Cap

func (p *PoolWithFunc) Cap() int

Cap returns the capacity of this pool.

func (*PoolWithFunc) Free

func (p *PoolWithFunc) Free() int

Free returns a available goroutines to work.

func (*PoolWithFunc) Invoke

func (p *PoolWithFunc) Invoke(args interface{}) error

Invoke submits a task to pool.

func (*PoolWithFunc) Reboot added in v2.3.0

func (p *PoolWithFunc) Reboot()

Reboot reboots a released pool.

func (*PoolWithFunc) Release

func (p *PoolWithFunc) Release()

Release Closes this pool.

func (*PoolWithFunc) Running

func (p *PoolWithFunc) Running() int

Running returns the number of the currently running goroutines.

func (*PoolWithFunc) Tune

func (p *PoolWithFunc) Tune(size int)

Tune changes the capacity of this pool.

Directories

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