Steve_BZ has asked for the wisdom of the Perl Monks concerning the following question:

Hi Guys,

I have some issues here with threads->new. However, it only fails in Komodo IDE 5 and Kubuntu 11.10. If I run from the command prompt, everything is cool. If I run from Komodo in Kubuntu 10.04, also, everything is cool. I have an app that generates some background tasks like an email with some large attachments. I don't want to wait while it sends so sending is a background task. It works like this:

if ( ref $next_job eq "Mail::Sender"){ $gl_thread_hsh{$gl_thread_hsh{next_thread}} = threads->new +( sub { my $result = $next_job->MailFile({ msg => $next_job->{msg}, file => $next_job->{file}, }); } ); $gl_thread_hsh{next_thread}=$gl_thread_hsh{next_thread}+1; + # Increment next available thread. }

Everything then crashes with this sort of error message (I don't think you want my whole stack-dump):

*** glibc detected *** /usr/bin/perl: double free or corruption (out): + 0x00007fff69bf35e0 *** ======= Backtrace: ========= /lib/x86_64-linux-gnu/libc.so.6(+0x7a6e6)[0x7fb82e4f76e6] /lib/x86_64-linux-gnu/libc.so.6(cfree+0x6c)[0x7fb82e4fb9cc] /usr/local/lib/perl/5.12.4/auto/Wx/Wx.so(+0x172e3c)[0x7fb82c745e3c] /usr/lib/libperl.so.5.12(Perl_pp_entersub+0x54d)[0x7fb82e8ce46d] /usr/lib/libperl.so.5.12(Perl_runops_standard+0x20)[0x7fb82e8c5c10] /usr/lib/libperl.so.5.12(Perl_call_sv+0x473)[0x7fb82e869cc3] /usr/lib/libperl.so.5.12(Perl_sv_clear+0x27a)[0x7fb82e8d3c0a] /usr/lib/libperl.so.5.12(Perl_sv_free2+0x52)[0x7fb82e8d4422] /usr/lib/libperl.so.5.12(Perl_sv_clear+0x725)[0x7fb82e8d40b5] /usr/lib/libperl.so.5.12(Perl_sv_free2+0x52)[0x7fb82e8d4422] /usr/lib/libperl.so.5.12(Perl_av_clear+0x158)[0x7fb82e8c3f88] /usr/lib/libperl.so.5.12(Perl_pp_entersub+0x7b3)[0x7fb82e8ce6d3]

I have also tried replacing use threads at the start of the program with require threads at call time. This doesn't help. My real issue is that this creates a blind-spot for debugging, in that issues in this area of code can't properly be debugged by single stepping through the code and examining variables, but only by print statments.

What are your thoughts, please?

Regards

Steve

Replies are listed 'Best First'.
Re: threads->new falling in a heap.
by BrowserUk (Patriarch) on May 11, 2012 at 11:39 UTC

    Is your program using Wx, or is that part of Komodo?


    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    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.

    The start of some sanity?

      Hi Browser,

      It's my application that is using Wx::.

      Steve

        In a nutshell, I think your chances of successfully debugging a multi-threaded, GUI application written in a dynamic language like perl, using a wiziwig IDE like Komodo are zero.

        Your expectations are too high.


        With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
        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.

        The start of some sanity?