Go Commons Pool

The Go Commons Pool is a generic object pool for Golang, direct rewrite from Apache Commons Pool.

Features

1. Support custom PooledObjectFactory.
2. Rich pool configuration option, can precise control pooled object lifecycle. See ObjectPoolConfig.
   • Pool LIFO (last in, first out) or FIFO (first in, first out)
   • Pool cap config
   • Pool object validate config
   • Pool object borrow block and max waiting time config
   • Pool object eviction config
   • Pool object abandon config

Pool Configuration Option

Configuration option table, more detail description see ObjectPoolConfig

Option	Default	Description
LIFO	true	If pool is LIFO (last in, first out)
MaxTotal	8	The cap of pool
MaxIdle	8	Max "idle" instances in the pool
MinIdle	0	Min "idle" instances in the pool
TestOnCreate	false	Validate when object is created
TestOnBorrow	false	Validate when object is borrowed
TestOnReturn	false	Validate when object is returned
TestWhileIdle	false	Validate when object is idle, see TimeBetweenEvictionRuns
BlockWhenExhausted	true	Whether to block when the pool is exhausted
MinEvictableIdleTime	30m	Eviction configuration,see DefaultEvictionPolicy
SoftMinEvictableIdleTime	math.MaxInt64	Eviction configuration,see DefaultEvictionPolicy
NumTestsPerEvictionRun	3	The maximum number of objects to examine during each run evictor goroutine
TimeBetweenEvictionRuns	0	The number of milliseconds to sleep between runs of the evictor goroutine, less than 1 mean not run

Usage

Use Simple Factory

import (
	"context"
	"fmt"
	"strconv"
	"sync/atomic"

	"github.com/jolestar/go-commons-pool/v2"
)

func Example_simple() {
	type myPoolObject struct {
		s string
	}

	v := uint64(0)
	factory := pool.NewPooledObjectFactorySimple(
		func(context.Context) (interface{}, error) {
			return &myPoolObject{
					s: strconv.FormatUint(atomic.AddUint64(&v, 1), 10),
				},
				nil
		})

	ctx := context.Background()
	p := pool.NewObjectPoolWithDefaultConfig(ctx, factory)

	obj, err := p.BorrowObject(ctx)
	if err != nil {
		panic(err)
	}

	o := obj.(*myPoolObject)
	fmt.Println(o.s)

	err = p.ReturnObject(ctx, obj)
	if err != nil {
		panic(err)
	}

	// Output: 1
}

Use Custom Factory

import (
	"context"
	"fmt"
	"strconv"
	"sync/atomic"

	"github.com/jolestar/go-commons-pool/v2"
)

type MyPoolObject struct {
	s string
}

type MyCustomFactory struct {
	v uint64
}

func (f *MyCustomFactory) MakeObject(ctx context.Context) (*pool.PooledObject, error) {
	return pool.NewPooledObject(
			&MyPoolObject{
				s: strconv.FormatUint(atomic.AddUint64(&f.v, 1), 10),
			}),
		nil
}

func (f *MyCustomFactory) DestroyObject(ctx context.Context, object *pool.PooledObject) error {
	// do destroy
	return nil
}

func (f *MyCustomFactory) ValidateObject(ctx context.Context, object *pool.PooledObject) bool {
	// do validate
	return true
}

func (f *MyCustomFactory) ActivateObject(ctx context.Context, object *pool.PooledObject) error {
	// do activate
	return nil
}

func (f *MyCustomFactory) PassivateObject(ctx context.Context, object *pool.PooledObject) error {
	// do passivate
	return nil
}

func Example_customFactory() {
	ctx := context.Background()
	p := pool.NewObjectPoolWithDefaultConfig(ctx, &MyCustomFactory{})
	p.Config.MaxTotal = 100
    
	obj1, err := p.BorrowObject(ctx)
	if err != nil {
		panic(err)
	}

	o := obj1.(*MyPoolObject)
	fmt.Println(o.s)

	err = p.ReturnObject(ctx, obj1)
	if err != nil {
		panic(err)
	}

	// Output: 1
}

For more examples please see pool_test.go and example_simple_test.go, example_customFactory_test.go.

Note

PooledObjectFactory.MakeObject must return a pointer, not value. The following code will complain error.

p := pool.NewObjectPoolWithDefaultConfig(ctx, pool.NewPooledObjectFactorySimple(
    func(context.Context) (interface{}, error) {
        return "hello", nil
    }))
obj, _ := p.BorrowObject()
p.ReturnObject(obj)

The right way is:

p := pool.NewObjectPoolWithDefaultConfig(ctx, pool.NewPooledObjectFactorySimple(
    func(context.Context) (interface{}, error) {
        s := "hello"
        return &s, nil
    }))

For more examples please see example_simple_test.go.

Dependency

• testify for test

PerformanceTest

The results of running the pool_perf_test is almost equal to the java version PerformanceTest

go test --perf=true

For Apache commons pool user

• Direct use pool.Config.xxx to change pool config
• Default config value is same as java version
• If TimeBetweenEvictionRuns changed after ObjectPool created, should call ObjectPool.StartEvictor to take effect. Java version do this on set method.
• No KeyedObjectPool (TODO)
• No ProxiedObjectPool
• No pool stats (TODO)

FAQ

FAQ

How to contribute

• Choose one open issue you want to solve, if not create one and describe what you want to change.
• Fork the repository on GitHub.
• Write code to solve the issue.
• Create PR and link to the issue.
• Make sure test and coverage pass.
• Wait maintainers to merge.

中文文档

• Go Commons Pool发布以及Golang多线程编程问题总结
• Go Commons Pool 1.0 发布

License

Go Commons Pool is available under the Apache License, Version 2.0.