Re: Thread initialization and condition

["Naveen Verma" <ernaveenverma gmail com>]

Hi,

I also tried the similar and very simple program on Ubuntu, and find similar behavior. It seems that thread creation takes longer time,  and we call the other member function i.e. fetch() before that. I did nothing but just printing the debug logs and log in fetch() print before that the loop(). 

And the same behavior with pthread also. May be thread creation and execution time varies between different OS and CPU?

May be we can have a queue between threads, one thread put the requests in queue and other thread reads and process from that?


-Br
Naveen

On Jan 4, 2008 3:06 PM, Joaquim Duran <joaquinduran adtelecom es> wrote:

En/na Andreas Volz ha escrit:

> Hello,
>
> I have a problem while running a thread application. Here is my code:
>
> Download::Download ()
> {
>   thread = Glib::Thread::create (sigc::mem_fun (*this,
>            &Download::threadFunc), true);
> }
>
> void Download::fetch ()
> {
>   // queue new files to download...
> }
>
> void Download::loop ()
> {
>   do
>   {
>     // download new files
>   }
>   while (1)
> }
>
> Ok, this was working on one machine. But now while testing it on
> another machine (also Linux) I got other results. This is how I use it:
>
>   Download dl;
>   dl.fetch (m_url, m_file);
>
> If I do debugging or print some debug messages I see that on one
> machine the thread loop() is entered before the fetch() function. I
> would expect that. But on the other machine the fetch() function is
> called before the thread loop().
>
> Couldn't I trust gtkmm that the thread loop is constructed and entered
> after returning the Glib::Thread::create() call?
>
> I tried to use some conditions to wait until the thread has entered. It
> worked, but only on one machine. The other one blocked forever. If this
> is a defined behaviour that I need to think about a more complex
> condition mechanism at initialization time.
>
> Gentoo:
> - gtkmm-2.10.10
> - thread loop() is called *before* fetch()
>
> Ubuntu:
> - libgtkmm-2.4-1c2a 1:2.12.0-0ubuntu1
> - thread loop() is called *after* fetch()
>
> Any ideas about that problem?
>
> regards
> Andreas
> _______________________________________________
> gtkmm-list mailing list
> gtkmm-list gnome org
> http://mail.gnome.org/mailman/listinfo/gtkmm-list
>
>

This looks like that there is no synchronization between main thread and
the FTP thread. The FTP thread should be waiting till main thread has
posted a new file to download and then start download.

GLibmm provides mutex and mutex-conditions to implement a
producer-consumer relation between threads.

Joaquim Duran
Thanks and Best Regards,

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