Re: advice needed for spinner

[tsuyoshi okita <825864 gmail com>]

Dear Brian,

Thank you very much for your tutorial.
I've been reading system programming in C. A baby step.

"With most GUI toolkits, Gtk2/Gtk3 included, you should never block the
process you run Gtk2/3 from, this will cause the UI to freeze."
yup, this is where I was stuck. Thank you for pointing out.

Once again thank you so much.

Tsuyoshi


On 2014年06月06日 12:26, Brian Manning wrote:
> Hi,
>
> Just to clarify a bit about forking and Gtk2 and Gtk3; when you use
> fork() to launch processes, if you want to get information from your
> child processes, you have to use a wait() call to wait for the
> children to exit; this will cause the parent process to block.
>
> With most GUI toolkits, Gtk2/Gtk3 included, you should never block the
> process you run Gtk2/3 from, this will cause the UI to freeze.
>
> Since you want to get information back from your child processes (so
> you know when to stop and hide the spinner), you need to use sockets,
> pipes, files, or some other type of interprocess communication (IPC)
> to pass data back from your child processes to the parent process,
> instead of having your parent process wait for your child processes to
> exit.  For example, you could shut off the spinner in the parent fork
> when your children fork(s) send the correct message to the parent fork
> via some kind of IPC.  You could also use threads and IPC to do the
> same thing.
>
> There are more examples floating around of using threads versus using
> forks with Gtk2, however, all of the examples that I have seen always
> use some kind of IPC to pass messages back and forth between
> parent/children processes in the case of forks, or amongst threads for
> threaded processes. Threads can also use message queues to pass
> messages back and forth between threads (but you can't pass blessed
> Perl objects via thread queues). There's not really any examples of
> IPC and threads/forks for Gtk3, but the procedure is the same between
> the two versions.
>
> I've included links to a few examples of both forks and threads with
> Gtk2/3 and IPC, more can be had if you ask your favorite search engine
> nicely (hint: try "perl gtk2 fork" or "perl gtk2 thread"), search in
> the mailing list archives, or go search on Perlmonks, zentara has
> written quite a few messages about threads on Perlmonks.
>
> Thanks,
>
> Brian
>
> URLs about forking/threading and using IPC in Gtk2:
>
> https://mail.gnome.org/archives/gtk-perl-list/2003-November/msg00033.html
> https://metacpan.org/source/XAOC/Gtk2-1.2491/examples/thread_usage.pl
> https://mail.gnome.org/archives/gtk-perl-list/2003-November/msg00028.html
>
> On Sun, Jun 1, 2014 at 4:50 PM, tsuyoshi okita <825864 gmail com> wrote:
> > Dear Guru,
> >
> > Thank you for your replies and time. I am no expert in this field.  I am
> > very sure you all have noticed by now*_*
> > I will study again with your codes provided.  Thank you, Marius and Zentara.
> > Brian, thank you for your effort.
> > Wax on, wax off, practice harder, Daniel-san!!
> > anyway, thank you again for your help.
> >
> > Tsuyoshi
> >
> >
> > On 2014年06月02日 02:24, zentara wrote:
> >
> > On Thu, 29 May 2014 11:27:27 +0900
> > tsuyoshi okita <825864 gmail com> wrote:
> >
> > Dear gurus,
> >
> > I've been trying let a spinner spins at the same time sending an email
> > by forking and failing.  Although a program forks, and one child process
> >
> > After reading all the replies by Brian Manning concerning
> > the difficulty of controlling the widget thru forks, I would
> > like to remind you that threads do a good job with this,
> > if you do it correctly.
> > ( My code below may not be correct, but it works. :-)
> >   See http://www.perlmonks.org?node_id=804402 for
> > a discussion.
> >
> > I'm not delving into Gtk3 yet, but the attached Gtk2 code
> > should be modifiable to Gtk3.
> >
> > 0m,
> > zentara
> >
> >
> >
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> >
> >
> >
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