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From André Warnier ...@ice-sa.com>
Subject Re: How can I prevent Quartz multiple execution after tomcatrestart
Date Mon, 26 Oct 2009 15:52:17 GMT
Christopher,

thanks for the masterful analysis.
I'll pick out just one aspect :

Christopher Schultz wrote:
...
> 
>> If it happened to be (2), then one could argue that adding an <Alias>
>> matching the real "Host:" of the calls, is actually slightly faster than
>> not doing so.
> 
My point exactly.

...
> 
>> One would just love to catch Chuck some time..
> 
> I'll bet he's quick: you'd better wear cleats and gloves.
> 
Yes, but this time..
Assuming there is a single (and default) Host, like this :
<Host name="locahost" ...>
   <Alias name="somealias.company.com">
</Host>

and multiple requests comes in with a header
Host: somealias.company.com

then indeed the fact of having this Alias, would be faster than not 
having it, wouldn't it ?
And in such a case, Chuck's comment that
"Note that if you have only one <Host>, <Alias> elements are completely 
superfluous."
would be, in fact, incorrect. Ha !

(I do mention "multiple requests", because one could also argue that if 
the number of requests addressing that particular "alias" is low, then 
the additional overhead of creating the alias-related Hosts array entry 
in the first place, may negate the subsequent efficiency gain.)
We need one of these nice graphs showing the respective gains here..
Don't you feel tempted ?

About your optimisation suggestions, I see another possible one :
If this is a keep-alive connection, then the same Tomcat thread will 
handle subsequent browser requests over that same connection.
As far as I know, there isn't really a case where a browser will issue 
multiple requests over the same connection, if not addressed to the same 
Host.  So the thread could also cache a pointer to the Host entry 
obtained in the first request of the connection, and re-use it without 
lookup for subsequent requests over the same connection.  Not so ?
(To make this more certain, one could also cache the Host's name and 
check, but that might not even be necessary).

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