some problem about prefetch and txsize

[andy lin]

Today I test the prefetch and txsize,but I find a problem as follows
this is my configuration

<rabbit:listener-container id="ocrWorker"
		concurrency="2" connection-factory="rabbitConnectionFactory"
		prefetch="3" transaction-manager="rabbitTransactionManager"
		transaction-size="20" auto-startup="false" message-converter="orcMessageConvert" >
		<rabbit:listener method="doMessageQueueWork"
			queue-names="queue.etlOcrServer.recognize" ref="ocrListener" />
	</rabbit:listener-container>

this is my rabbitmq server pic ,the prefetch and txsize recording on the server not equals with the configuration
dsdsd.jpg

but the value of Prefetch count in rabbitServer equals with the transaction-size,not prefetch.Could you explain the reason.In my opinion ,transaction-size,means if the amount of client processing the message succefully reach the value,client will send ack to server,it can make server works better instead of sending a ack per message.The prefetch means client can get some messages saving on the local machine,and the mq server will wait for the ack reaching.Is my opinions correct?

[Gary Russell]

See the java doc; the prefetch should always be greater or equal to the transaction size.

	/**
	 * Tells the broker how many messages to send to each consumer in a single request. Often this can be set quite high
	 * to improve throughput. It should be greater than or equal to {@link #setTxSize(int) the transaction size}.
	 *
	 * @param prefetchCount the prefetch count
	 */

[andy lin]

Thanks I forget the relationship