The GUI is hang

My program's GUI is hang(The gui is not start). I attachd it process(gdb -p pid).

The following is backtrace.

Code:

---

(gdb) info thread
* 1 Thread 0x7f9bc495a760 (LWP 13482)  0x0000003c822f0dee in __lll_lock_wait_private ()
   from /lib64/libc.so.6
(gdb) bt
#0  0x0000003c822f0dee in __lll_lock_wait_private () from /lib64/libc.so.6
#1  0x0000003c8227c138 in _L_lock_9164 () from /lib64/libc.so.6
#2  0x0000003c82279a32 in malloc () from /lib64/libc.so.6
#3  0x0000003c8226fcfb in __libc_message () from /lib64/libc.so.6
#4  0x0000003c82275676 in malloc_printerr () from /lib64/libc.so.6
#5  0x0000003c8227ab57 in _int_realloc () from /lib64/libc.so.6
#6  0x0000003c8227acb5 in realloc () from /lib64/libc.so.6
#7  0x00007f9bc49f449b in QListData::realloc (this=0x11f6f38, alloc=2)
    at /var/tmp/qt-x11-src-4.5.1/src/corelib/tools/qlistdata.cpp:111
#8  0x00007f9bc49f4569 in QListData::append (this=0x11f6f38)
    at /var/tmp/qt-x11-src-4.5.1/src/corelib/tools/qlistdata.cpp:131
#9  0x00007f9bc4ad4a5b in QList<QObjectPrivate::Connection>::append (this=0x11f6f38, t=...)
    at ../../include/QtCore/../../src/corelib/tools/qlist.h:426
#10 0x00007f9bc4accd9c in QObjectPrivate::addConnection (this=0x11f5cc0, signal=11, c=0x7fff2cf9d2e0)
    at /var/tmp/qt-x11-src-4.5.1/src/corelib/kernel/qobject.cpp:277
#11 0x00007f9bc4acd8c4 in QMetaObject::connect (sender=0x11f5c30, signal_index=11, receiver=
    0x11f6460, method_index=29, type=1, types=0x0)
    at /var/tmp/qt-x11-src-4.5.1/src/corelib/kernel/qobject.cpp:2808
#12 0x00007f9bc4acf8f6 in QObject::connect (sender=0x11f5c30, signal=<value optimized out>, receiver=
    0x11f6460, method=<value optimized out>, type=4294966784)
    at /var/tmp/qt-x11-src-4.5.1/src/corelib/kernel/qobject.cpp:2545
#13 0x000000000040cdde in main (argc=1, argv=0x7fff2cf9d5f8) at paramon.cpp:28

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The main.cpp:28 is "QObject::connect(render,SIGNAL(renderedPixmap(con st QImage &)),canvas,SLOT(updatePixmap(const QImage &)),Qt::DirectConnection);".

Any help will be appreciated.

Show your main() please.

The following is my main code.

Code:

---

int main(int argc,char **argv)
{
  qDebug()<<"Main Begin";
  QApplication app(argc,argv);
 
  MCanvas *canvas=new MCanvas;
  MRender *render=new MRender;
  MZoom *zoom=new MZoom;
  //if(NULL==zoom)qDebug()<<"zomm is null";
  //QObject::connect(render,SIGNAL(rendered(const QImage &)),canvas,SLOT(updateImage(const QImage &)));
  QObject::connect(render,SIGNAL(rendered(const QImage &)),canvas,SLOT(updateImage(const QImage &)),Qt::DirectConnection);  // This is the hang line
  render->start();
  zoom->start();
 
  QWidget *widget=new QWidget;
  widget->resize(800,600);
  QGridLayout *layout=new QGridLayout(widget);
  layout->addWidget(canvas);
  layout->setContentsMargins(0,0,0,0);
  widget->setLayout(layout);
  widget->show();
 
  app.exec();
  delete render;
  delete widget;
  qDebug()<<"Main End";
 
  return 0;
}

---

As wysota already told you in the other thread (btw, thanks for duplicating the topic), you cannot create a QPixmap in any other thread then the one running the QApplication event loop (here the main thread).

Cheers,
_

Quote:

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As wysota already told you in the other thread (btw, thanks for duplicating the topic), you cannot create a QPixmap in any other thread then the one running the QApplication event loop (here the main thread).

---

Thanks for your attention.
This is the different with that thread.
My code has been improved for many times. And some problems are resolved, some new problems come in.
I had removed QPixmap from any other thread.

Please prepare a minimal compilable example reproducing the problem.

Sorry, it worksforme.
It happend when I add "zoomMessage_="Who am I?";" to class MZoom constructor.
And I don't have enough information to reproduce it now too.
I ask redhat in the following link https://bugzilla.redhat.com/show_bug.cgi?id=1160557.