partitions.go
func (c *partitionConsumer) AsyncClose() {
	c.closeOnce.Do(func() {
		c.closeErr = c.PartitionConsumer.Close()
		close(c.dying)
	})
}
func (c *partitionConsumer) AsyncClose() {
	c.closeOnce.Do(func() {
		c.closeErr = c.PartitionConsumer.Close()
		close(c.dying)
	})
}
// AsyncClose implements PartitionConsumer