[Qt-interest] sockets and threads on linux

[pmqt71]

I'm still learning Qt and I want to be aware of various way to do the
work, so I'm going  to implement both solutions (single and multi-threaded
socket I/O). Now I'm going to debug the readyRead signal not working on
linux...
Really appreciate your suggestions.
pm.



2011/2/14 Jason H <scorp1us at yahoo.com>

>  Thiago and I respectfully disagree on our philosophy to use threads when
> using sockets.
> He says never, and I say anything above the trivial.
>
> The fully async behavior of Qt's implementation means you don't have to use
> threads. You can do just fine without them... in most cases. And you can do
> just fine when having a GUI in the same thread too.
>
> I use threads anytime the request could take substantial CPU. For most
> types of network traffic, when there is significant I/O delay or trivial
> computation involved in the network data. There won't be a scalability
> issue. (Serving a file will wait on disks for the most part, or it'll all be
> in cache, either way, single thread is fine)
>
> I however prefer to offer SSL/TLS everywhere, and having it multithreaded
> will help distribute the encryption load over all cores. My computations
> were lengthy in nature, could use compression if the client requested it.
> For light loads (< 50 clients) I could serve at 80% to full speed. After
> that, it dropped off. My specs required I be able to service within specific
> time frames at higher loads, so I went multithreaded.
>
> It's not much harder to make it multithreaded, so if I think I might want
> it, then I do it from the start. If you're new and want to just get it
> working, then it's not a mistake to keep it single threaded and cross that
> bridge when you come to it.
>
>
>
>
>
>
>
>
>
>  ------------------------------
> *From:* pmqt71 <pmqt71 at gmail.com>
> *To:* Thiago Macieira <thiago at kde.org>; qt-interest at trolltech.com
> *Sent:* Sun, February 13, 2011 6:24:32 PM
> *Subject:* Re: [Qt-interest] sockets and threads on linux
>
>
> Hi Thiago,
> I'd like to make the thread solution working in order to better understand
> the related concepts with Qt.
> It actually works on XP: threads, sockets, events... it's working very well
> with hundreds of clients.
>
>  Are you suggesting me to avoid threads with sockets for a
> performance/optimization issue? or do you know about a possible problem?
>
> thanks
> pm
>
> 2011/2/13 Thiago Macieira <thiago at kde.org>
>
>> On Sunday, 13 de February de 2011 17:42:06 pmqt71 wrote:
>> > Hi all,
>> > Hi Qt people, I hope the best for Qt and you!
>> >
>> > I have a tcp client server program working well on WinXP, but not on
>> linux.
>> >
>> > MyTcpServer inherits from QTcpServer. the incomingConnection method
>> creates
>> > a new socket and moves it to a new thread. The socket is handled by
>> > MyTcpSocket that inherits from QTcpSocket and implements the slots to
>> manage
>> > client's incoming data:
>>
>> Why? Why do you insist in using threads for networking I/O after I told
>> you
>> last week that you don't need to?
>>
>> Use the thread to do the actual processing of the data. Not for the
>> networking.
>>
>> > On linux (Ubuntu 9.04 64bit) the readyRead signal is not fired. The
>> > incomingConnection is completed with no error, the pSocket objects gets
>> the
>> > event ThreadChange related to the moveToThread operation. Nothing else.
>> > How can I debug?
>> > Qt 4.6.2
>>
>> First of all, upgrade.
>>
>> Second, debug the moveToThread call and check if the socket notifiers and
>> the
>> socket engine got moved to the other thread. While debugging moveToThread,
>> you
>> should be able to identify any children that got moved along with it.
>>
>> Alternatively, or in addition, you can also put some breakpoints or
>> debugging
>> information in the register and unregisterSocketNotifier functions in the
>> event
>> dispatcher classes (QEventDispatcherUNIX or QEventDispatcherGlib). You
>> should
>> see the socket notifier be registered for the main thread, unregistered,
>> then
>> re-registered in the other thread.
>>
>> --
>> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
>>  Senior Product Manager - Nokia, Qt Development Frameworks
>>      PGP/GPG: 0x6EF45358; fingerprint:
>>      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
>>
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>>
>
>
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