Qt QRunnable错误

Question

我使用QRunnable时遇到问题。当我试图从线程发出信号时，我遇到了运行时错误。有我的代码：

curlthread.cpp
void CurlThread::run() {
    qDebug()<<"Thread started"<<act();

    qDebug()<<"1234";
    emit error(url(),act());
    qDebug()<<"5678";
    return;
    if (system(NULL)) {
        int result = system(cmd.toStdString().c_str());
        if (result) {
            emit error(url(),act());
            //proxy()->emitCurlError(m_url,m_act);
        }
    }
}
curlthread.h
class CurlThread : public QObject, public QRunnable
{
    Q_OBJECT
public:
    explicit CurlThread(QObject *parent = 0);
    .....

protected:
    void run();
signals:
    void error(QString,QString);
...
};

curlproxy.cpp
void CurlProxy::rateRU(QVariant var1, QVariant var2) {
    CurlThread* thread = new CurlThread;
    thread->setAct(var1.toString());
    thread->setUrl(var2.toString());
    QThreadPool::globalInstance()->start(thread);
    connect(thread, &CurlThread::error, this, &CurlProxy::curlError, Qt::QueuedConnection);
}

void CurlProxy::curlError(QString url, QString act) {
    qDebug()<<"emit error";
    qDebug()<<url;
    qDebug()<<m_nonRated.count();
    m_nonRated.push_back(QPair<QString,QString>(url,act));
}

curlproxy.h
class CurlProxy : public QObject
{
    Q_OBJECT
public:
    explicit CurlProxy(QObject *parent = 0);
    Q_INVOKABLE void rateRU(QVariant , QVariant );
    void emitCurlError(QString,QString);

signals:
public slots:
    void curlError(QString,QString);
...
};

我的代码的主要思想是我调用CurlProxy.rateRU（...）并从该函数启动CurlThread。在CurlThread :: run我只是尝试向主线程发出信号，但有时候我遇到了崩溃。有例子日志：

[D] CurlThread::run:9 - Thread started "431376" 
[D] CurlThread::run:15 - 1234 
[D] CurlProxy::curlError:18 - emit error 
[D] CurlProxy::curlError:19 - "rulez" 
[D] CurlProxy::curlError:20 - 0 
[D] CurlThread::run:17 - 5678 
[D] onPressAndHold:43 - ident is 431375 index 1
[D] CurlThread::run:9 - Thread started "431375" 
[D] CurlThread::run:15 - 1234 
[D] CurlThread::run:17 - 5678 
Application crashed