3.5 线程池基本用法

#include <QCoreApplication>
#include <QDebug>
#include <QRunnable>
#include <QThread>
#include <QThreadPool>
class MyRun : public QRunnable
{
public:
    MyRun()
    {
    }
    ~MyRun()
    {
    }
public:
    void run()
    {
        int i = 3;
        while (i)
        {
            i--;
            qDebug() << "thread start:" << QThread::currentThreadId();
            QThread::msleep(500);
        }
    }
};
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    qDebug() << "Main:" << QThread::currentThreadId();
    QThreadPool m;
    m.setMaxThreadCount(2);
    m.setExpiryTimeout(-1);
    MyRun *run = new MyRun;
    if (!run->autoDelete())
    {
        qDebug() << "QRunnable's autoDelete default value is not true";
        run->setAutoDelete(true);
    }
    qDebug() << m.maxThreadCount() << m.expiryTimeout();
    qDebug() << m.activeThreadCount();
    m.start(run);
    qDebug() << m.activeThreadCount();
    m.waitForDone();
    qDebug() << m.activeThreadCount();
    return 0;
}

3.6 线程池内的子线程发信号

需要派生QObject！

class MyThread_draw2D_SectionChart : public QObject, public QRunnable
{
    Q_OBJECT
public:
    MyThread_draw2D_SectionChart(int frameNo) :
  m_iFrameNo(frameNo)
    {
    }
    virtual ~MyThread_draw2D_SectionChart()
    {
  qDebug() << "~MyThread";
    }
public:
    virtual void run();
private:
    int m_iFrameNo;
signals:
    void sig_updateUI_SectionChart(int frameNo);
};

4、子线程发信号给主线程，更新UI

通过信号槽的机制可以实现，子线程发信号给主线程即可。不会阻塞。

启动线程

m_future_2d_SectionChart = QtConcurrent::run(this, &FormContent::thread_draw2D_SectionChart);

子线程

void FormContent::thread_draw2D_SectionChart(void)//绘制2D截面图

{

qDebug() << "sub thread id:" << QThread::currentThreadId();

connect(this, SIGNAL(sig_updateUI_SectionChart()), this, SLOT(slot_updateUI_SectionChart()));

while (true)

{

//去主线程更新UI

 emit sig_updateUI_SectionChart();

}

}

主线程

void FormContent::slot_updateUI_SectionChart(void)//更新2D截面图

{

  qDebug() << "main thread id:" << QThread::currentThreadId();

m_pFormTimeline->updateSectionChart();

}

5、数据保护，加锁解锁

QMutex 提供相互排斥的锁，或互斥量；有递归和非递归之分；

QMutexLocker 是一个辅助类，自动对 QMutex 加锁与解锁；

QReadWriterLock 提供了一个可以同时读操作的锁；有递归和非递归之分；

QReadLocker与QWriteLocker 自动对QReadWriteLock 加锁与解锁；

QSemaphore 提供了一个整型信号量，是互斥量的泛化；

QWaitCondition 提供了一种方法，使得线程可以在被另外线程唤醒之前一直休眠。

https://doc.qt.io/qt-5/qmutex.html

https://doc.qt.io/qt-5/qmutexlocker.html

https://doc.qt.io/qt-5/qreadlocker.html

https://doc.qt.io/qt-5/qwritelocker.html

https://doc.qt.io/qt-5/qreadwritelock.html

https://doc.qt.io/qt-5/qsemaphore.html

https://blog.csdn.net/guoyufeng25/article/details/103105244

6、线程优先级

Qthread的优先级属性：Priority指示系统如何调度线程。

QThread::IdlePriority 0

scheduled only when no other threads are running.

QThread::LowestPriority 1

scheduled less often than LowPriority.

QThread::LowPriority 2

scheduled less often than NormalPriority.

QThread::NormalPriority 3

the default priority of the operating system.

QThread::HighPriority 4

scheduled more often than NormalPriority.

QThread::HighestPriority 5

scheduled more often than HighPriority.

QThread::TimeCriticalPriority 6

scheduled as often as possible.

QThread::InheritPriority 7

use the same priority as the creating thread. This is the default.

x、多线程的高级应用

TCP Client/TCP Server

https://sourceforge.net/projects/threader-qt/

https://sourceforge.net/p/threader-qt/svn/HEAD/tree/

future/promise【推荐】

https://github.com/mhogomchungu/tasks

y、参考文献

https://github.com/czyt1988/czyBlog/tree/master/tech/QtThread

https://www.cnblogs.com/xia-weiwen/p/10306089.html

https://github.com/Xia-Weiwen/CopyFile