From: Warren Young
Date: August 6 2009 9:52pm
Subject: Re: Automatic Reconnect
List-Archive: http://lists.mysql.com/plusplus/8698
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On Aug 6, 2009, at 3:42 PM, Dan Cook (dancook) wrote:

> The rub comes from connections that have not expired in the pool  
> after a
> server restart - the next grab will fail (I just tested this using  
> gdb).
> I don't think there is anything a programmer can do about this except
> retry.

Yes.  Even ping-on-grab() isn't 100% foolproof, as the DB server or  
network link could bounce between a successful ping and the query.   
So, if you either need a bulletproof system or these are common cases  
for you, you still need connection retry logic.

> But then how do you purge (expire) all the connections in the
> pool to get them to reset and do a fresh reconnect?

Ping-on-grab() would handle that.  I don't see a compelling reason to  
special-case this, dumping all the connections at once.  Just handle  
it as part of your normal connection robustness assurance code.