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From Niklas Therning <>
Subject Re: [mina] Thread Pools, Concurrent connections and Performance
Date Tue, 27 Dec 2005 14:12:51 GMT
Alessandro Torrisi wrote:
> IoThreadPoolFilter f = (IoThreadPoolFilter)
> reg.getIoAcceptor(TransportType.SOCKET).getFilterChain().get("threadPool");
> f.setMaximumPoolSize(10);
> I discovered that this piece of code gives me  "NullPointerException", I 
> have no FilterChain applied to the Acceptor and in my Eclipse debugger I 
> can see:

 From what I can tell from the code you have included below you are 
using MINA 0.9. As I explained in my previous mail the code above will 
only work in MINA 0.8 (in 0.9 you will get an NPE since f will be null). 
In MINA 0.9 you can try to to extend SimpleServiceRegistry instead as I 
described earlier:

public class MyServiceRegistry extends SimpleServiceRegistry {
     public MyServiceRegistry() {

Please note that the most important thing for scalability is that you 
never perform any blocking operations in your IoHandler implementation. 
Or at least make sure that they only block for a very short time. The 
code samples you included do not give enough information on whether you 
have any blocking operations.

> ...
> I'm stopped ! I don't know where to look. I think there's too little 
> documentation or too few examples for Mina, I think more complex samples 
> are needed !
> Regards, Alex

Yes, you may be right about that. But your open source DC server will be 
an excellent example of a more complex MINA application. In the meantime 
the MINA community is here to help you out.

BTW, is your open source project hosted somewhere publicly like on 
sourceforge? If it is I could have a look if you want to.


> Niklas Therning wrote:
>> No, the number of threads in your thread pool does not limit the 
>> number of concurrent clients. That's actually one of the big benefits 
>> of using MINA. Since everything is event based you can use a small 
>> number of threads to handle a larger number of connections.
>> Please, try to set the max pool size to a small number (5-10 maybe) 
>> and see if this has any impact on the performance.
>> /Niklas
>> Alessandro Torrisi wrote:
>>> But in this way I will limit users max number in the hub server I 
>>> think...
>>> Is there any way to have a significant increase of performance ?
>>> Regards,
>>> Alex.
>>> Niklas Therning wrote:
>>>> Alessandro Torrisi wrote:
>>>>> Hi ! I'm developing a free and opensource Direct Connect software 
>>>>> (P2P server). Now that protocol implementation is quite complete 
>>>>> I'm testing with lot of connections.
>>>>> When connections are made in a concurrent way (50-100 a time), the 
>>>>> server seems to be blocked...
>>>>> Can I do something to improve performance, adjusting some parameter 
>>>>> or applying some programming pattern directly on Mina ? I've 
>>>>> listened about Thread Pools on SocketAcceptor and IoThreadPool but 
>>>>> I didn't find any tutorial or documentation, is it possible to 
>>>>> directly configure these ones ?
>>>> Yes. By default the maximum thread pool size equals 
>>>> Integer.MAX_VALUE. It can be changed but this has changed bewteen 
>>>> MINA 0.8 and 0.9.
>>>> In 0.8, when using SimpleServiceRegistry, you can configure the 
>>>> maximum pool size like this:
>>>> IoThreadPoolFilter f = (IoThreadPoolFilter)
>>>> reg.getIoAcceptor(TransportType.SOCKET).getFilterChain().get("threadPool");

>>>> f.setMaximumPoolSize(10);
>>>> In 0.9 its not that easy since the ThreadPoolFilter used by 
>>>> SimpleServiceRegistry isn't accessible until a session has been 
>>>> created. You could try to extend SimpleServiceRegistry and configure 
>>>> the protected threadPoolFilter yourself:
>>>> public class MyServiceRegistry extends SimpleServiceRegistry {
>>>>     public MyServiceRegistry() {
>>>>         super();
>>>>         threadPoolFilter.setMaximumPoolSize(10);
>>>>     }
>>>> }
>>>> And then instead of using SimpleServiceRegistry you use 
>>>> MyServiceRegistry.
>>>> Both of these approaches will use a thread pool of at most 10 threads.
>>>> HTH
>>>> /Niklas

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