Infinite loop when closing window

clydemcqueen

Hi, I built and ran the videoplayer example. I'm using the code exactly as written. I'm have Qt5.12.8 on Ubuntu 20.04. My build environment is CLion with the OSRF ament macros; here's the CMake file I'm using:

cmake_minimum_required(VERSION 3.5)
project(videoplayer)

set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTORCC ON)

find_package(ament_cmake REQUIRED)
find_package(Qt5Widgets REQUIRED)
find_package(Qt5Multimedia REQUIRED)
find_package(Qt5MultimediaWidgets REQUIRED)

add_executable(
  videoplayer
  main.cpp
  videoplayer.cpp
)

ament_target_dependencies(
  videoplayer
  Qt5Widgets
  Qt5Multimedia
  Qt5MultimediaWidgets
)

ament_package()

This compiles and runs just fine. If I run from the command line and hit Ctrl-C, then app closes cleanly. But when I close the window by clicking on the windows-close box I get a seg fault. Valgrind tells me that the stack can't grow, which makes me suspect an infinite loop:

==168367== Stack overflow in thread #1: can't grow stack to 0x1ffe801000
==168367== 
==168367== Process terminating with default action of signal 11 (SIGSEGV)
==168367==  Access not within mapped region at address 0x1FFE801FF8
==168367== Stack overflow in thread #1: can't grow stack to 0x1ffe801000
==168367==    at 0x4C89C7D: QWidget::setAttribute(Qt::WidgetAttribute, bool) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.12.8)

In CLion's debug window I do in fact see an infinite loop:

<repeated>
QWidget::create(unsigned long long, bool, bool) 0x00007f5f20b35f83
QWidgetPrivate::createWinId() 0x00007f5f20b36295
QWidget::create(unsigned long long, bool, bool) 0x00007f5f20b35f83
QWidgetPrivate::createWinId() 0x00007f5f20b36295
QWidget::create(unsigned long long, bool, bool) 0x00007f5f20b35f83
QWidgetPrivate::createWinId() 0x00007f5f20b36295
QWidget::create(unsigned long long, bool, bool) 0x00007f5f20b35f83
QWidgetPrivate::createWinId() 0x00007f5f20b36295
QWidget::create(unsigned long long, bool, bool) 0x00007f5f20b35f83
QWidgetPrivate::createWinId() 0x00007f5f20b36295
QWidgetPrivate::createWinId() 0x00007f5f20b362c8
QWidget::winId() const 0x00007f5f20b36313
QGstreamerVideoWidgetControl::eventFilter(QObject*, QEvent*) 0x00007f5f18206d50
QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) 0x00007f5f1ffcf64b
QApplicationPrivate::notify_helper(QObject*, QEvent*) 0x00007f5f20b00a55
QApplication::notify(QObject*, QEvent*) 0x00007f5f20b0a0f0
QCoreApplication::notifyInternal2(QObject*, QEvent*) 0x00007f5f1ffcf93a
QWidgetPrivate::setWinId(unsigned long long) 0x00007f5f20b33612
QWidget::destroy(bool, bool) 0x00007f5f20b37572
QWidget::~QWidget() 0x00007f5f20b3ec45
QGstreamerVideoWidgetControl::~QGstreamerVideoWidgetControl() 0x00007f5f1820708e
QGstreamerVideoWidgetControl::~QGstreamerVideoWidgetControl() 0x00007f5f182070ed
QObjectPrivate::deleteChildren() 0x00007f5f1fff901e
QObject::~QObject() 0x00007f5f200035ef
<unknown> 0x00007f5f18c46efb
<unknown> 0x00007f5f208d5963
QMediaPlayer::~QMediaPlayer() 0x00007f5f2091706d
QMediaPlayer::~QMediaPlayer() 0x00007f5f2091709d
QObjectPrivate::deleteChildren() 0x00007f5f1fff901e
QWidget::~QWidget() 0x00007f5f20b3ec29
VideoPlayer::~VideoPlayer videoplayer.cpp:53
main main.cpp:24
__libc_start_main 0x00007f5f1f9820b3
_start 0x000055876228dc8e

Any ideas?

Thanks in advance,
/Clyde

jeremy_k

@clydemcqueen said in Infinite loop when closing window:

It looks like you have encountered https://bugreports.qt.io/browse/QTBUG-87325

clydemcqueen

@jeremy_k Yes, looks like it. Thanks.