Qt QCoreApplication :: exec（）在Ubuntu 12.04上崩溃
[英]qt QCoreApplication::exec() crash on ubuntu 12.04
问题描述
I am developing a system application with signal slot on sockets in qt, ubuntu 
我正在开发在Qt，Ubuntu的套接字上具有信号插槽的系统应用程序
void Receiver::startServer()
{
....
connect(udpSocket, SIGNAL(readyRead()), this, SLOT(receiveFunc()));
}
void Receiver::receiveFunc()
{
emit receiveForwarder();
{
Handler::start()
{
receiver= new Receiver();
thread=new QThread()
receiver->moveToThread(thread);
receiver->startServer();
connect(receiver, SIGNAL(receiveForwarder()), this, SLOT(processTexts()));
}
Handler::processTexts()
{
//emit another signal that is in another thread
}
I have a processTexts function that is either a slot for a thread and also emits a signal to another thread. 我有一个processTexts函数，它既是线程的插槽，也向另一个线程发出信号。 If I omit the second emit in Handler the problem is not solved but program crashes somewhat later. 如果我省略了Handler中的第二个send，问题仍然无法解决，但是程序稍后会崩溃。 But it does not disapear. 但这并没有消失。 it creashes after a minute or two. 一两分钟后它就会皱折。 program processes texts that comes from UDP socket. 程序处理来自UDP套接字的文本。 and sends it via another QTcpSocket to another program. 并通过另一个QTcpSocket将其发送到另一个程序。
The crash signature is : 崩溃签名是：
0[bt:0]/application/collector/main.cpp::exceptionHandler(int)::30
./collector(_Z16exceptionHandleri+0x56)[0x422156]
/lib/x86_64-linux-gnu/libc.so.6(+0x364c0)[0x7fbf348f54c0]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(+0x1a9b24)[0x7fbf35558b24]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_check+0x183)[0x7fbf33db1a33]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x47f96)[0x7fbf33db1f96]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_iteration+0x34)[0x7fbf33db2124]
/usr/lib/x86_64-linugnu-libQtCore.so.4(_ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEven tsFlagEE+0xd6)[0x7fbf35559426]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN10QEventLoop13processEventsE6QFlagsINS_17ProcessEventsFlagEE+0x32) [0x7fbf35528c82]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE+0xf7) [0x7fbf35528ed7]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN16QCoreApplication4execEv+0x87)[0x7fbf3552df67]
./collector(main+0x216)[0x4234c6]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xed)[0x7fbf348e076d]
I analyzed it with valgrind and it says: 我用valgrind分析了它，并说：
==31981== Conditional jump or move depends on uninitialised value(s)
==31981== at 0x556AB14: ??? (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x6C2AA32: g_main_context_check (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2AF95: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2B123: g_main_context_iteration (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x556B3BE: QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AC81: QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AED6: QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553FF66: QCoreApplication::exec() (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x4234C5: main (main.cpp:170)
==31981==
==31981== Invalid read of size 2
==31981== at 0x556AB45: ??? (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x6C2AA32: g_main_context_check (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2AF95: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2B123: g_main_context_iteration (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x556B3BE: QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AC81: QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AED6: QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553FF66: QCoreApplication::exec() (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x4234C5: main (main.cpp:170)
==31981== Address 0xa8bf0c6 is 6 bytes inside a block of size 16 free'd
==31981== at 0x4C2A4BC: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31981== by 0x556AB44: ??? (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x6C2AA32: g_main_context_check (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2AF95: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2B123: g_main_context_iteration (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x556B3BE: QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AC81: QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AED6: QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553FF66: QCoreApplication::exec() (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x4234C5: main (main.cpp:170)
==31981==
==31981== Invalid read of size 2
==31981== at 0x556AB4D: ??? (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x6C2AA32: g_main_context_check (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2AF95: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2B123: g_main_context_iteration (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x556B3BE: QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AC81: QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AED6: QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553FF66: QCoreApplication::exec() (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x4234C5: main (main.cpp:170)
==31981== Address 0xa8bf0c4 is 4 bytes inside a block of size 16 free'd
==31981== at 0x4C2A4BC: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31981== by 0x556AB44: ??? (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x6C2AA32: g_main_context_check (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2AF95: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2B123: g_main_context_iteration (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x556B3BE: QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AC81: QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AED6: QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553FF66: QCoreApplication::exec() (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x4234C5: main (main.cpp:170)
==31981==
==31981== Thread 2:
==31981== Invalid write of size 2
==31981== at 0x6C281FA: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C291D1: g_source_add_poll (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x556B7A9: QEventDispatcherGlib::registerSocketNotifier(QSocketNotifier*) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x5145E59: QUdpSocket::readDatagram(char*, long long, QHostAddress*, unsigned short*) (in /usr/lib/x86_64-linux-gnu/libQtNetwork.so.4.8.1)
==31981== by 0x4205F1: LogReceiver::receiveLog() (udpSocket.cpp:52)
==31981== by 0x42B630: LogReceiver::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) (moc_udpSocket.cpp:54)
==31981== by 0x5555445: QObject::event(QEvent*) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553BE9B: QCoreApplication::notifyInternal(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553FC69: QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x556AF92: ??? (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x6C2AC99: g_main_context_dispatch (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2B05F: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== Address 0xa8bf0c6 is 6 bytes inside a block of size 16 free'd
==31981== at 0x4C2A4BC: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31981== by 0x556AB44: ??? (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x6C2AA32: g_main_context_check (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2AF95: ??? (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x6C2B123: g_main_context_iteration (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.3200.1)
==31981== by 0x556B3BE: QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AC81: QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553AED6: QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x553FF66: QCoreApplication::exec() (in /usr/lib/x86_64-linux-gnu/libQtCore.so.4.8.1)
==31981== by 0x4234C5: main (main.cpp:170)
I analyzed the program and I removed all my bugs I do not know if it is a Qt bug or ubuntu bug or GCC or my fault. 我分析了程序，并删除了所有我不知道是Qt还是ubuntu还是GCC还是我的错误的错误。
Besides I wanted to know if anybody tried a system application with more than 20 events per second. 此外，我想知道是否有人每秒尝试20个以上事件的系统应用程序。 It crashes after a while. 一段时间后崩溃。
Thank you all in advance. 谢谢大家。
1 个解决方案
解决方案1
0 2012-08-30 11:38:28
SocketNotifier implementation is not thread safe. SocketNotifier实现不是线程安全的。 That means that you are not allowed to control it from different threads. 这意味着不允许您从其他线程控制它。
If you have Qt compiled without QT_NO_DEBUG you will receive warning that you control it from different threads: 如果您在没有QT_NO_DEBUG的情况下编译了Qt，则会收到警告，提示您可以从其他线程控制它：
void QEventDispatcherGlib::unregisterSocketNotifier(QSocketNotifier *notifier)
{
Q_ASSERT(notifier);
#ifndef QT_NO_DEBUG
int sockfd = notifier->socket();
if (sockfd < 0) {
qWarning("QSocketNotifier: Internal error");
return;
} else if (notifier->thread() != thread()
|| thread() != QThread::currentThread()) {
qWarning("QSocketNotifier: socket notifiers cannot be disabled from another thread");
return;
}
#endif
//....
}
Please check if all member of object, that is moved to thread, are created as a child of this object. 请检查是否已将对象的所有成员（移到线程中）创建为该对象的子对象。 Or just switch off QT_NO_DEBUG. 或者只是关闭QT_NO_DEBUG。
BTW: I struggled with similar problem and the crash appears after few hours of usage. 顺便说一句：我为类似的问题而苦苦挣扎，使用数小时后出现了崩溃。
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