缓冲区溢出使用Qt线程和信号 [英] Buffer Overrun using Qt Threads and Signals

问题描述

我必须将一个项目从QT5降级到QT4，并得到一个奇怪的缓冲区溢出错误这样做。这是我的代码：

我创建一个QThread如此：

  thread = new QThread; 
 reader = new Reader（）; 
 
 reader-> setParams（samplingRate）; 
 reader-> moveToThread（thread）; 
 connect（thread，SIGNAL（started（）），reader，SLOT（read（）））; 
 connect（reader，SIGNAL（finished（）），thread，SLOT（quit（）））; 
 connect（thread，SIGNAL（finished（）），this，SLOT（threadFinished（）））; 
 connect（reader，SIGNAL（finished（）），reader，SLOT（deleteLater（）））; 
 connect（thread，SIGNAL（finished（）），thread，SLOT（deleteLater（）））; 
 connect（reader，SIGNAL（errorMsg（QString）），this，SLOT（threadErrorMsg（QString）））; 
 thread-> start（）; 
  

在我的线程中，我有以下代码：

  try {
 while（condition）{
 ... something 
} 
} catch（Exception e）{
 emit errorMsg（Error）; 
} 
 emit finished（）; 
  

我的主线程中的Slots如下：

  void MainWindow :: threadFinished（）{
 reader = NULL; 
 delete thread; 
 thread = NULL; 
} 
 
 void MainWindow :: threadErrorMsg（QString message）{
 QMessageBox :: critical（this，Error，（Error：+ message）.toStdString .c_str（），QMessageBox :: Ok）; 
} 
  

所有这些都在QT5中运行良好。错误消息框正确显示，线程已销毁。然而在QT4（4.8.1）中，当发生错误和发出errorMsg（）时，我得到缓冲区溢出错误。如果我不发出errorMsg（Error）并且只通过调用finished（）来销毁线程，就不会发生缓冲区溢出。任何想法，在这里错了什么？

更新：
如果我不访问QString在threadErrorMsgit工作。像这样：

  void MainWindow :: threadErrorMsg（QString message）{
 QMessageBox :: critical ，Error，QMessageBox :: Ok）; 
} 
  

我做错了什么？

解决方案

  void MainWindow :: threadFinished（）{
 reader = NULL; 
 delete thread; 
 thread = NULL; 
} 
  

不建议直接删除插槽中的线程。您应该使用deleteLater函数。

  thread-> deleteLater但是，您已经在连接中设置要删除的主题
 $ b 
 
 
 
 
 
 $ b 
  connect（thread，SIGNAL（finished（）），thread，SLOT（deleteLater 
  
因此，您现在尝试删除它两次！
 
 
 
对于缓冲区溢出，我怀疑在错误发生之前，有东西损坏了内存。 
 
I have to downgrade a project from QT5 to QT4 and get a weird buffer overrun error when doing so. Here's my code: 

I create a QThread like so: 
thread = new QThread;
reader = new Reader();

reader->setParams(samplingRate);
reader->moveToThread(thread);
connect(thread, SIGNAL(started()), reader, SLOT(read()));
connect(reader, SIGNAL(finished()), thread, SLOT(quit()));
connect(thread, SIGNAL(finished()), this, SLOT(threadFinished()));
connect(reader, SIGNAL(finished()), reader, SLOT(deleteLater()));
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
connect(reader, SIGNAL(errorMsg(QString)), this, SLOT(threadErrorMsg(QString)));
thread->start();
In my thread I have the following code:
try {
     while(condition) {
         ...something
     }
} catch(Exception e) {
     emit errorMsg("Error");
}
emit finished();
And the Slots in my main thread look like this: 
void MainWindow::threadFinished() {
    reader = NULL;
    delete thread;
    thread = NULL;
}

void MainWindow::threadErrorMsg(QString message) {
    QMessageBox::critical(this, "Error", ("Error: " + message).toStdString().c_str(), QMessageBox::Ok);
}
All of this worked well in QT5. The error message box was displayed correctly and the thread was destroyed. In QT4 (4.8.1) however I get a buffer overrun error when an error occurs and errorMsg() is emitted. The buffer overrun does not occur if I don't emit the errorMsg("Error") and destroy the thread only by calling finished(). Any ideas on what's wrong here? 

Update: 
If i don't access the QString in threadErrorMsgit does work. Like so: 
void MainWindow::threadErrorMsg(QString message) {
    QMessageBox::critical(this, "Error", "Error", QMessageBox::Ok);
}
What am I doing wrong?
解决方案
void MainWindow::threadFinished() {
    reader = NULL;
    delete thread;
    thread = NULL;
}
Deleting the thread directly in the slot is not advised. You should use the deleteLater function.
thread->deleteLater();
However, you've already setup the thread to be deleted in the connection
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
So you're now trying to delete it twice!

As for the buffer-overrun, I suspect something has corrupted memory before the error has occurred. 

                        
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