syncx

README

syncx

1. syncx.Pool

Defects of sync.Pool

1. Get/Put func is unbalanced on P.
   1. Usually Get and Put are not fired on the same goroutine, which will result in a difference in the fired times of Get and Put on each P. The difference part will trigger the steal operation(using CAS).
2. poolLocal.private has only one.
   1. Get/Put operations are very frequent. In most cases, Get/Put needs to operate poolLocal.shared (using CAS) instead of the lock-free poolLocal.private.
3. Frequent GC.
   1. sync.Pool is designed to serve objects with a short life cycle, but we just want to reuse, don’t want frequent GC.

Optimize of syncx.Pool

1. Transform poolLocal.private into an array to increase the frequency of poolLocal.private use.
2. Batch operation poolLocal.shared, reduce CAS calls.
3. Allow No GC.

Not Recommended

1. A single object is too large.
   1. syncx.Pool permanently holds up to runtime.GOMAXPROC(0)*256 reusable objects.
   2. For example, under a 4-core docker, a 4KB object will cause about 4MB of memory usage.
   3. please evaluate it yourself.

Performance

benchmark	sync ns/op	syncx ns/op	delta
BenchmarkSyncPoolParallel-4(p=16)	877	620	-29.30%
BenchmarkSyncPoolParallel-4(p=1024)	49385	33465	-32.24%
BenchmarkSyncPoolParallel-4(p=4096)	255671	149522	-41.52%

Example

var pool = &syncx.Pool{
	New: func() interface{} {
		return &struct{}
	},
	NoGC: true,
}

func getput() {
	var obj = pool.Get().(*struct)
	pool.Put(obj)
}

2. syncx.RWMutex

Documentation

Index

• type Pool
  • func (p *Pool) Get() (x interface{})
  • func (p *Pool) Put(x interface{})
• type RWMutex
  • func NewRWMutex() RWMutex
  • func (m RWMutex) Lock()
  • func (m RWMutex) RLocker() sync.Locker
  • func (m RWMutex) Unlock()

Types

type Pool

type Pool struct {

	// New optionally specifies a function to generate
	// a value when Get would otherwise return nil.
	// It may not be changed concurrently with calls to Get.
	New func() interface{}
	// NoGC any objects in this Pool.
	NoGC bool
	// contains filtered or unexported fields
}

func (*Pool) Get

func (p *Pool) Get() (x interface{})

Get selects an arbitrary item from the Pool, removes it from the Pool, and returns it to the caller. Get may choose to ignore the pool and treat it as empty. Callers should not assume any relation between values passed to Put and the values returned by Get.

If Get would otherwise return nil and p.New is non-nil, Get returns the result of calling p.New.

func (*Pool) Put

func (p *Pool) Put(x interface{})

Put adds x to the pool.

type RWMutex

type RWMutex []rwMutexShard

RWMutex is a p-shard mutex, which has better performance when there's much more read than write.

func NewRWMutex

func NewRWMutex() RWMutex

NewRWMutex creates a new RWMutex.

func (RWMutex) Lock

func (m RWMutex) Lock()

func (RWMutex) RLocker

func (m RWMutex) RLocker() sync.Locker

func (RWMutex) Unlock

func (m RWMutex) Unlock()