Beefy Boxes and Bandwidth Generously Provided by pair Networks Joe
Problems? Is your data what you think it is?
 
PerlMonks  

threads and their alternatives

by metaperl (Curate)
on Sep 30, 2011 at 15:27 UTC ( #928837=note: print w/ replies, xml ) Need Help??


in reply to Re: Alternatives to threads for maintaining GUI app responsiveness
in thread Alternatives to threads for maintaining GUI app responsiveness

Our single-threaded GUI app was freezing whenver we did dateabase reads and it looked like the app had crashed. Therefore we threaded the app and visual response significantly improved.

What alternatives are there to our problem

You had a problem, you solved it. Why are you looking for alternatives?
Because I like to know the pros and cons of possible solutions. Especially considering the fact that mst said perl threads sucked. Now, he did refuse to explain why, but he did mention those other CPAN modules as alternatives. And I also made it clear that my solution was potentially redundant/conflicting becuase Glib already had threads
(Ps. Why, uniquely do you feel the need to ask your questions in Big Bold Lettering? Are they somehow more important than other peoples questions?)
Each of us is a fingerprint of God, dont superimpose your fingerprint and its tendencies on mine.... or even waste your time in criticism. But anyway, I like to take the semantic aspects of my posts and use the visual layout to distinguish them.


Comment on threads and their alternatives
Re: threads and their alternatives
by BrowserUk (Pope) on Sep 30, 2011 at 15:47 UTC
    I like to know the pros and cons of possible solutions.

    Threads are built-in, simple, portable and are working for you now.

    The rest are non-portable add-ons, with huge learning curves, that produce complicated, hard to maintain code.

    And they don't have a solution to fundamentally blocking apis like DBI.

    Your question might make some sense if you had specific problems with the threaded solution, but it seems you are allowing the validity of your working code to be questioned on the basis of its 'coolness' with a particular group of people, who "don't like threads" but can't explain why. That's not good reasoning.


    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

      As an aside, AnyEvent is fairly portable and has a solution to blocking APIs like DBI. Whether that solution is really a good solution stands to debate - it spawns an external process which executes the fetch and then passes the results back via IPC. In principle, this idea isn't all bad, except that I wouldn't use one external process per query but a separate thread that does all database interaction.

        AnyEvent is fairly portable

        Really? Does it work with files and pipes under Windows?

        Does AnyEvent::DBI work on Windows? Cos you certainly wouldn't think so looking at the source:

        my $pid = fork; if ($pid) { # parent close $server; } elsif (defined $pid) { # child my $serv_fno = fileno $server; if ($self->{exec_server}) { fcntl $server, &Fcntl::F_SETFD, 0; # don't close the server s +ide exec {$^X} "$0 dbi slave", -e => "require shift; AnyEvent::DBI::serve_fd ($serv_fno +, $VERSION)", $INC{"AnyEvent/DBI.pm"}; POSIX::_exit 124; } else { ($_ != $serv_fno) && POSIX::close $_ for $^F+1..$FD_MAX; serve_fh $server, $VERSION; # no other way on the broken windows platform, even this leak +s # memory and might fail. kill 9, $$ if AnyEvent::WIN32; # and this kills the parent process on windows POSIX::_exit 0; } } else { croak "fork: $!"; } $self->{child_pid} = $pid; $self->_req ( ($self->{on_connect} ? $self->{on_connect} : sub { }), (caller)[1,2], req_open => $dbi, $user, $pass, %dbi_args ); $self }
        has a solution to blocking APIs like DBI. ... it spawns an external process which executes the fetch and then passes the results back via IPC.

        I guess I could have said "don't have a good solution", but I don't consider starting a new process for each query and then having to squeeze potentially large amounts of structured data through a byte stream, a solution worthy of the name.


        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
      with huge learning curves, that produce complicated, hard to maintain code.

      Can't agree with this statement, I had to work with some projects with POE and AnyEvent and it wasn't especially hard to learn and maintain. On the other hand I will not call threads simple, as most people (I'm judging by code I had to work with) either had no idea that they need to lock shared variable before accessing it at all, or are not able to implement it properly.

        Would you be up for the challenge of producing a demo solution for the OPs described problem using one of the event-based frameworks?

        If so, I'll do a threaded version and we could compare them for complexity.

        If you're up for it, we could start with a simple GUI in Tk or GTK that presents data as a list -- zentara has posted many examples we could use as a starting point -- and then we add a few buttons that are used to control which records are SELECTed from a simple SQLite database using an SQL query via DBI.

        Contrasting two working solutions would be far more useful that contrasting our opinions I think.


        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://928837]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others about the Monastery: (15)
As of 2014-04-17 14:23 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    April first is:







    Results (449 votes), past polls