c++ - QThread : Destroyed while thread is still running in QTest

Question

我写了一个小的多线程消息队列。现在，我正在尝试进行测试。但是我遇到了无法解决的同步问题。
如果我删除了队列中的所有内容，则最小的可验证示例如下所示(抱歉，它有点大):

#include <QCoreApplication>
#include <QDebug>
#include <QTimer>
#include <QtTest/QtTest>

#include <random>
#include <thread>

static std::vector< int > dummy;

class Writer : public QObject {
    Q_OBJECT

public:
    Writer( QObject *parent = nullptr ) : QObject( parent ) { }
    Writer( unsigned, QObject *parent = nullptr ) : QObject( parent ) { }

public:
    const std::vector< int > &beginPendings( ) { return dummy; }
    void endPendings( ) { }

Q_SIGNALS:
    void haveEvents( );

public Q_SLOTS:
    void start( ) {
        m_stop.test_and_set( );

        connect( &m_inputTimer, &QTimer::timeout, this, &Writer::onTimer );
        m_inputTimer.start( 100U );
        connect( &m_outputTimer, &QTimer::timeout, this, &Writer::notifyEvents );
        m_outputTimer.start( 250U );
    }

    void stop( ) {
        m_inputTimer.stop( );
        m_outputTimer.stop( );
    }

private Q_SLOTS:
    void onTimer( ) {
        int limit = dist( mt );

        for( int idx = 0; idx < limit; ++idx ) {
            ++m_idx;
        }
    }

    void notifyEvents( ) {
        emit haveEvents( );
    }

private:
    QTimer m_inputTimer;
    QTimer m_outputTimer;
    int m_idx = 0;
    std::atomic_flag m_stop = ATOMIC_FLAG_INIT;
    std::random_device rd;
    std::mt19937 mt{ rd( ) };
    std::uniform_int_distribution< int > dist{ 1, 20 };
};

class InOutQueueTest: public QObject {
    Q_OBJECT

public Q_SLOTS:
    void onPendingEvents( void ) {
        writer->endPendings( );
    }

    void onTimeout( ) {
        writer->stop( );
        backendThread->exit( 0 );
        backendThread->deleteLater( );

        stop = true;
    }

private Q_SLOTS:
    void limit15( ) {
        finishTimer.setSingleShot( true );
        finishTimer.start( 5000 );

        backendThread = new QThread( );
        writer = new Writer( 15U );

        connect( &finishTimer, &QTimer::timeout, this, &InOutQueueTest::onTimeout );
        connect( writer, &Writer::haveEvents, this, &InOutQueueTest::onPendingEvents );

        writer->moveToThread( backendThread );

        backendThread->start( );
        writer->start( );

        while( !stop ) {
            QCoreApplication::processEvents( );
        }
    }

private:
    Writer *writer;
    QThread *backendThread;
    int last = 0;
    QTimer finishTimer;
    bool stop = false;
};

QTEST_GUILESS_MAIN( InOutQueueTest )

#include "inoutqueue.moc"

我希望测试能持续5秒钟，并正确结束。但是，我得到:

WARNING: InOutQueueTest::limit15() Generate 19 numbers, starting at 517
Loc: [/home/juanjo/Trabajos/qml/test/inoutqueue.cpp(53)]
WARNING: InOutQueueTest::limit15() Generate 19 numbers, starting at 536
Loc: [/home/juanjo/Trabajos/qml/test/inoutqueue.cpp(53)]
QFATAL : InOutQueueTest::limit15() QThread: Destroyed while thread is still running
FAIL! : InOutQueueTest::limit15() Received a fatal error.
Loc: [Unknown file(0)]
Totals: 1 passed, 1 failed, 0 skipped, 0 blacklisted, 5068ms
********* Finished testing of InOutQueueTest *********
Aborted

应该结束测试(5秒后)的代码是这样的:

void onTimeout( ) {
    writer->stop( );
    backendThread->exit( 0 );
    backendThread->deleteLater( );

    stop = true;
}

我在 stop( )中调用 Writer方法，在辅助线程中调用 exit( )方法，然后在事件循环的下一次迭代中将其删除(这是理论上的)。
同样，在 Writer类中， stop( )方法为:

void stop( ) {
    m_inputTimer.stop( );
    m_outputTimer.stop( );
}

我只是停止两个计时器。

我在做什么错？

我该如何解决？

Answer 1

在删除线程之前，您需要始终在该线程上添加wait()(在非Qt中说“join”)。
在QThread上调用exit()会立即返回，并且不会等待。并且deleteLater()在调用者的线程(不是目标线程)中执行，因此您不能指望它被称为“足够晚”。
先执行exit()，然后执行wait()，然后执行deleteLater()。