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From Carl Trieloff <cctriel...@redhat.com>
Subject Re: QPID C++ Broker + persistent store
Date Mon, 23 Feb 2009 16:12:23 GMT

> Well, I do not understand why the synchronous IO mode is no longer
> supported. My experiences of queueing tell me that if you want really safe
> message store you need synchronous IO on message PUT. But maybe did I miss
> some new things which make this feature deprecated ?
>
>   

This is a great question:

The key is that the C++ broker is that it is an async process, so the 
broker has all the logic to know when all the async processing on a 
message is complete. So even with a async store, the broker will not ack 
the client until the message/update is physically written to disk. Given 
this there is no advantage to a sync mode. Async is faster in all cases 
- and all the exact same message guarantees are provided using  async.

The only reason the sync option was there was to enable testing while 
the async impl was been hardened.

regards
Carl.






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