[rabbitmq-discuss] persistence

Wed May 14 20:46:08 BST 2008

Lars,

Lars Bachmann wrote:
> 1. if my producer sends only a small amount of messages (lets say  
> 5000), then all queues receive all messages persistent and everything  
> is ok
> 2. if my producer sends a larger amount of messages (lets say 100000),  
> then some strange behaviour appears. All queues receive only some of  
> this messages. Sometimes 80% sometimes 50% sometimes even only 10% =>  
> i couldnt discover any pattern, it seemed to be just random

Could you send us the client code, please? I'd like to try reproducing this.

> So Im wondering why this happens. Could it be that there are too many  
> messages to persist and the broker cant handle it because of i dont  
> know too less memory or some like this ?

The way you described it above, the messages should certainly get routed 
to (and persisted by) all the queues.

Are there any errors in the server logs?

> Another question: Lets say we have 5 subscriber (each listen to his  
> "own" queue) in the pub / sub scenario and we want persistent message  
> storing. Does this mean that each messages is stored 5 times ? (and  
> for n subscribers n times which would cause a big overhead)

In a non-clustered setup only one copy of the message is stored. In a 
cluster we store one copy of the message *per node* that has queues to 
which the message was routed.

Matthias.