Hi, it could be a timeout of the lock used in QSettings.
- Michael. -----Original Message----- From: Interest [mailto:interest-bounces+sue=sf.mpg...@qt-project.org] On Behalf Of william.croc...@analog.com Sent: Tuesday, November 8, 2016 2:56 PM To: interest@qt-project.org Cc: Thiago Macieira <thiago.macie...@intel.com> Subject: Re: [Interest] [PROGRESS] Long pause with 5.7 On 11/07/2016 07:22 PM, william.croc...@analog.com wrote: > This sender failed our fraud detection checks and may not be who they > appear to be. Learn about spoofing at http://aka.ms/LearnAboutSpoofing > >>> >>> I am porting my app to Qt 5.7 >>> When I run it, it appears on the screen, but there is a long pause >>> (~10 secs.) before it is responsive. >>> I ran it with strace and there is a point where it makes 100K calls >>> to the poll() function, which accounts for the long pause. >>> I tried running it in a debugger, but the app does not exhibit the >>> pause in that context. >> >> Sounds like a threading race condition and running in the debugger >> changes the timing just enough. >> > > Gave the debugger another try. On some occasions, it would take the > long pause. (The pause is more like 5 seconds.) If I interrupt it, > this is the stack trace. > Note that it is in the call to show() which precedes my call to > exec(). > > Bill > > #0 0x0000003b0a0df113 in poll () from /lib64/libc.so.6 > #1 0x0000003b0bc449f9 in ?? () from /lib64/libglib-2.0.so.0 > #2 0x0000003b0bc44e4c in g_main_context_iteration () from > /lib64/libglib-2.0.so.0 > #3 0x00007ffff55b2740 in > QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () > from > /nobackup/whc/qt/5.7.0-shared-debug-64Bit-RH6-NoOpenGL/qtbase/lib/libQ > t5Core.so.5 > #4 0x00007ffff5565229 in > QCoreApplication::processEvents(QFlags<QEventLoop::ProcessEventsFlag>, int) () > from > /nobackup/whc/qt/5.7.0-shared-debug-64Bit-RH6-NoOpenGL/qtbase/lib/libQ > t5Core.so.5 > #5 0x000000000098c60b in MyProg::show (this=0x7fffffffb8d0) at > prog.cpp:562 > #6 0x0000000000986551 in MyMain (argc=@0x7fffffffc15c: 1, > argv=0x7fffffffc2f8) at prog.cpp:151 > #7 0x0000000000986ad9 in main (argc=1, argv=0x7fffffffc2f8) at > yoda.cpp:221 > I did not notice the call to show() was a call *MY* show(). My bad, but there is still something funny going on. Since the beginning of time I have been searching for the way to restore window positions and sizes when a user reenters my app. This is especially tricky under X windows with the separate client/server, various window managers and window decorations. Following is part of my solution. It appears that with Qt 5.7, SOMETIMES, my call to processEvents waits for the full 5 secs even though I do not believe there is anything to do. That is why my app is SOMETIMES unresponsive for 5 seconds when I start it up. void MyApp::show() { QSize sz; QPoint pos; { QSettings settings; sz = settings.value("MainWindowWSize",QSize(1200,700)).toSize(); pos = settings.value("MainWindowPos",QPoint(180,190)).toPoint(); } if( sz.width() > 0 && sz.height() > 0 ) { resize(sz); move(pos); } BaseClass::show(); qApp->flush(); // It appears that with Qt 5.7, SOMETIMES, this call to processEvents waits // for the full 5 secs though I do not believe there is anything to do. qApp->processEvents(QEventLoop::ExcludeUserInputEvents,5000); if( sz.width() > 0 && sz.height() > 0 ) { resize(sz); move(pos); } raise(); } _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
