mysql-proxy-discuss team mailing list archive

[Kay Röpke <Kay.Roepke@xxxxxxx>]

Hi!

On Jul 18, 2009, at 10:31 AM, Urban Loesch wrote:

> It takes 3 minutes for the proxy to know that one backend is down or  
> not reachable because of some network interruptions.
>
> I made some tests and I "DROP" all connections from the proxy to the  
> first backend with the firewall. So I can simulate a possible  
> network interruption to backend 1.
>
> With "netstat" I followed the proxy connection and I see for 3  
> minutes a "SYN_SENT" to backend 1, before the proxy is changing the  
> connection to   backend 2.
>
> For me it's very important that this timeout is as low as possible,  
> perhaps 15 Seconds will be enough.


I'm not sure this is possible because of the way TCP/IP works.  
Generally systems don't allow tuning the various timeouts employed in  
TCP.
Someone with more intimate knowledge of TCP/IP stacks might want to  
chime in here, to correct me if possible.

Otherwise, I'm afraid we would need some kind of alarm thread or look  
at using other timeout mechanisms for the non-blocking I/O we do to  
implement this.
If nothing comes out of this discussion, please file a feature request  
at bugs.mysql.com (against Proxy/Core).

cheers,
-k
--
Kay Roepke
Software Engineer, MySQL Enterprise Tools

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