Re: [jetty-users] Scalability of ProxyServlet$Transparent and Tomcat

[Jesse McConnell <jesse.mcconnell@xxxxxxxxx>]

also, the proxy servlet works well leveraging the jetty-continuations
api which was the mechanism for having async servlets on servlet 2.5
which is normally not possible

if you are using it on tomcat then the async aspect is falling back to
polling as opposed to true long polling

at this point we have no plans to port the proxy servlet to use
servlet 3.0 but I suppose we might at some point

cheers,
jesse

--
jesse mcconnell
jesse.mcconnell@xxxxxxxxx


On Thu, Jul 26, 2012 at 11:15 AM, Joakim Erdfelt <joakim@xxxxxxxxxxx> wrote:
> Sounds like you need to ask Tomcat what is going on.
>
> We can help you sort out issue if you run the transparent proxy on jetty
> itself.
> As we ... well .. wrote the jetty server, we should know how it works inside
> out. :-)
>
> --
> Joakim Erdfelt <joakim@xxxxxxxxxxx>
> www.webtide.com
> Developer advice, services and support
> from the Jetty & CometD experts.
>
>
>
> On Thu, Jul 26, 2012 at 8:14 AM, Gian Luca Ortelli
> <gianluca.ortelli@xxxxxxxxxxx> wrote:
>>
>> Hi,
>>
>> I have set up a basic web application to try out the Transparent servlet.
>> The relevant block of my web.xml reads:
>>
>>   <servlet>
>>       <servlet-name>proxy</servlet-name>
>>
>> <servlet-class>org.eclipse.jetty.servlets.ProxyServlet$Transparent</servlet-class>
>>       <init-param>
>>           <param-name>ProxyTo</param-name>
>>           <param-value>http://localhost:8080/</param-value>
>>       </init-param>
>>       <init-param>
>>           <param-name>Prefix</param-name>
>>           <param-value>/</param-value>
>>       </init-param>
>>       <load-on-startup>1</load-on-startup>
>>       <async-supported>true</async-supported>
>>   </servlet>
>>
>> I'm using version 8.1.1.v20120215 of jetty-servlet, and I'm deploying to
>> Tomcat 7.0.21.
>>
>> A server is listening on http://localhost:8080/, and it takes 5 seconds to
>> serve each request that it receives (the response is a few characters).
>>
>> In my tests I'm firing several simultaneous requests to the server,
>> proxied through the Transparent servlet.
>>
>> Now, from what I know about the Transparent, I would expect that Tomcat's
>> HTTP thread pool doesn't limit the number of concurrent requests; as soon as
>> a new request comes in, it should be immediately handed over to a thread of
>> Transparent's own pool, which in turn does the proxying job using
>> asynchronous IO.
>>
>> Instead, what I observe is that the size of Tomcat's pool IS the limit for
>> concurrent requests. Did I misunderstand the functioning and purpose of the
>> Transparent? Or is this just a "feature" of the combination Tomcat + Jetty
>> servlet?
>>
>> Hoping that someone will shed some light on this.
>>
>> Greetings,
>>   Gianluca
>>
>>
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>
>
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