GUI hangs under linux

[SpanishJohn]

Hi all,

I have written a GUI client for out hardware switch. The GUI runs fine under win32 but will hang as soon as I open a dialog and attempt an edit within the dialog when running under Linux (64-bit)

I have placed the following code in 'main' which helps some

#ifndef WIN32

// It is only necessary to call this function if multiple threads might use Xlib concurrently (and this should *not* be the case - I think!)
XInitThreads();

#endif

Not sure where to start on this one. Has anyone seen similar?

Regards, SJ

[SGaist]

Hi,

Without code it's crystal ball debugging. Can you show your main.cpp for a start ?

[SpanishJohn]

Yes. Sorry I realize it was a bit vague

Here is my main:

int main(int argc, char *argv[])
{
config_t config;

#ifndef WIN32

// It is only necessary to call this function if multiple threads might use Xlib concurrently (and this should *not* be the case - I think!)
XInitThreads();

#endif

fprintf(stderr, "\n");

if (config_t::load(argc, argv, &config) != 1)
{
    return -1;
}

Q_INIT_RESOURCE(backhaul_gui);

QApplication app(argc, argv);

QCoreApplication::setOrganizationDomain("AlteraDomain");
QCoreApplication::setOrganizationName("Altera");
QCoreApplication::setApplicationName(APP_NAME);
QCoreApplication::setApplicationVersion("1.0.0");

#ifndef WIN32

app.setStyle("windowsxp");

#endif

backhaul_gui backhaul_gui(config);

backhaul_gui.setMinimumSize(1200, 600);

if (!backhaul_gui.initialise())
{
    QMessageBox::warning(NULL, QObject::tr(APP_NAME),
                         QObject::tr("Unable to initialise. Application terminating."),
                         QMessageBox::Ok);

    return -1;
}

// Get the thread ID of the main thread
g_thread_id = QThread::currentThreadId();

return app.exec();

}

The app opens and has the option to open the 'connect with server' dialog. The dialog requires an IP address and a socket number. I only have to press the mouse button in the edit box and she hangs...

BRgds, SJ

[SpanishJohn]

@int main(int argc, char *argv[])
{
config_t config;

#ifndef WIN32

XInitThreads();

#endif

fprintf(stderr, "\n");


if (config_t::load(argc, argv, &config) != 1)
{
    return -1;
}

Q_INIT_RESOURCE(backhaul_gui);

QApplication app(argc, argv);

QCoreApplication::setOrganizationDomain("AlteraDomain");
QCoreApplication::setOrganizationName("Altera");
QCoreApplication::setApplicationName(APP_NAME);
QCoreApplication::setApplicationVersion("1.0.0");

#ifndef WIN32

app.setStyle("windowsxp");

#endif

backhaul_gui backhaul_gui(config);

backhaul_gui.setMinimumSize(1200, 600);

if (!backhaul_gui.initialise())
{
    QMessageBox::warning(NULL, QObject::tr(APP_NAME),
                         QObject::tr("Unable to initialise. Application terminating."),
                         QMessageBox::Ok);

    return -1;
}

// Get the thread ID of the main thread
g_thread_id = QThread::currentThreadId();

return app.exec();

}@
A better main :)

SJ

[SpanishJohn]

The application is statically built with Qt 4.7.4

SJ

[SpanishJohn]

Hi again. More details.

The application always hangs when I go to edit the socket number.

here is the code for the corresponding slot:

@void api_connect_t::edit_socket(QString str)
{
if (str.length() > 0)
{
m_socket = str.toInt();
}
}@

If I remove the

@XInitThreads();@

from main and run this is what I get:

bq. X Error: BadImplementation (server does not implement operation) 17
Major opcode: 20 (X_GetProperty)
Resource id: 0x0
Xlib: sequence lost (0x10000 > 0x99eb) in reply type 0x0!
X Error: 0 0
Major opcode: 0 ()
Resource id: 0x2c484d0
X Error: 0 0
Major opcode: 0 ()
Resource id: 0x132
X Error: 0 0
Major opcode: 0 ()
Resource id: 0x0
X Error: 0 0
Major opcode: 0 ()
Resource id: 0x0
Xlib: sequence lost (0x10000 > 0xa9c3) in reply type 0xe7!
Xlib: sequence lost (0x10000 > 0xa9c3) in reply type 0xe7!
Xlib: sequence lost (0x10000 > 0xaa9b) in reply type 0x0!
X Error: 0 0
Major opcode: 0 ()
Resource id: 0x0
Xlib: sequence lost (0x10000 > 0xaa9b) in reply type 0x1!
Xlib: unexpected async reply (sequence 0x0)!
Killed

Now, if I do this to my socket slot the problem appears to go away:

@void api_connect_t::edit_socket(QString str)
{
return;

if (str.length() > 0)
{
    m_socket = str.toInt();
}

}@

Very strange!!

SJ

[SGaist]

First, why do you need XInitThreads ?

[SpanishJohn]

Hi.

I use XInitThreads because it makes a bad situation slightly better. However it does not solve the problem so ideally it should not be there. Without it I get the screen dump shown above almost immediately on opening my simple dialog.

My application does implement a worker thread that is used for the client layer of my app, where as all GUI related work is done by the main thread. I have been very careful to avoid the worker thread directly manipulating widgets - on the rare event that such manipulation is required I use the following method to
ensure the worker does not directly drive the widget.

@QCoreApplication::postEvent(g_gui, new progress_event_t(0));@

As it happens the crash shown above happens when the worker thread is idle (running usleep) .

SJ

[SGaist]

How does your application behave if you don't have that worker thread active ?

[SpanishJohn]

Hi. OK so I commented out the code that starts the worker thread and -

she hung immediately :(

which confirms its not the worker thread that's causing the problem. I'm out of ideas.

SJ

[SGaist]

Then start your application from scratch adding one element after another until it hangs