code: func (pool *SyncPool) Alloc(size int) []byte {
  	if size <= pool.maxSize {
  		for i := 0; i < len(pool.classesSize); i++ {
  			if pool.classesSize[i] >= size {
  				mem := pool.classes[i].Get().(*[]byte)
  				return (*mem)[:size]
  			}
  		}
  	}
  	return make([]byte, size)
  }
docs: // Alloc try alloc a []byte from internal slab class if no free chunk in slab class Alloc will make one.