我在网上找到了几个教程，解释了如何在长时间计算期间更新 QProgressBar。其中之一是：使用 QThread 进行计算，然后发出连接到progressBar.setValue(int).
我认为这也必须适用于同时运行的几个 QThread，但有些东西不能正常工作。
所以，这就是我要做的：我想计算几个粒子的轨迹（每个粒子都有一个长循环）。为了使用多核处理，我为这些粒子中的每一个创建了一个 QThread，并让它调用各自的计算方法。这工作正常，所有核心都被使用，计算完成时间比以前大约四分之一。
我根据本教程http://mayaposch.wordpress.com/2011/11/01/how-to-really-truly-use-qthreads-the-full-explanation/编写了一个 Worker 类。标头如下所示：(worker.h)
#include <world.h>
class Worker: public QObject
{
Q_OBJECT
public:
explicit Worker(World *world = 0, double deltaTau = 0., double maxDist = 0., double iterations = 0., double index = 0);
public slots:
void process();
signals:
void finished();
void eror(QString err);
private:
World *w;
double my_deltaTau;
double my_maxDist;
int my_iterations;
int my_index;
};
像这样的来源：（worker.cpp）
#include "worker.h"
Worker::Worker(World *world, double deltaTau, double maxDist, double iterations, double index)
{
w = world;
my_deltaTau = deltaTau;
my_maxDist = maxDist;
my_iterations = iterations;
my_index = index;
}
void Worker::process()
{
w->runParticle(my_deltaTau, my_maxDist, my_iterations, my_index);
emit finished();
}
在 world.cpp 中，我有一个run启动所有线程的函数和runParticleWorker 调用的函数：
void World::run(double deltaTau, double maxDist, int iterations)
{
globalProgress = 0;
for (int j = 0; j < particles->size(); j++) { //loop over all particles
QThread *thread = new QThread;
Worker *worker = new Worker(this, deltaTau, maxDist, iterations, j);
worker->moveToThread(thread);
connect(thread, SIGNAL(started()), worker, SLOT(process()));
connect(worker, SIGNAL(finished()), thread, SLOT(quit()));
connect(worker, SIGNAL(finished()), thread, SLOT(deleteLater()));
connect(thread, SIGNAL(finished()), worker, SLOT(deleteLater()));
thread->start();
}
}
void World::runParticle(double deltaTau, double maxDist, int iterations, int index)
{
for (int i = 0; i < iterations; i++) { //loop over iteration steps
if (i % 1000 == 0) { //only update the progress bar every 1000th iteration
emit updateProgress(++globalProgress);
qApp->processEvents(); // <--- I added this line, no effect!
}
[...] // <--- do my calculations for the particle's trajectories
}
}
updateProgress(int)每 1000 次迭代步骤调用一次公共槽。它连接到我的 MainWindow 中的 QProgressBar，如下所示：
progressBar->setValue(0);
progressBar->setMaximum(nrPart * iter / 1000); //number of particles * number of iteration steps / 1000
connect(world, SIGNAL(updateProgress(int)), progressBar, SLOT(setValue(int)));
world->run(timeStep, dist, iter);
我的问题是进度条在所有计算完成之前不会移动，然后我看到它很快就会移动到 100%。
有没有人看到我的错误或知道如何正确地做到这一点？
编辑
我做了以下更改：
(工人.h)
#include "world.h"
class Worker: public QObject
{
Q_OBJECT
public:
explicit Worker(World *world = 0, Particle *particle = 0, QList<MagneticField> *bfields = 0, double deltaTau = 0., double maxDist = 0., int iterations = 0);
public slots:
void process();
signals:
void finished();
void updateProgress(int value);
void ProcessParticle();
void eror(QString err);
private:
int i;
Particle *p;
QList<MagneticField> *magneticFields;
double my_deltaTau;
double my_maxDist;
int my_iterations;
};
（工人.cpp）
#include "worker.h"
Worker::Worker(World *world, Particle *particle, QList<MagneticField> *bfields, double deltaTau, double maxDist, int iterations)
{
i = 0;
const World *w = world;
p = particle;
magneticFields = bfields;
my_deltaTau = deltaTau;
my_maxDist = maxDist;
my_iterations = iterations;
connect(this, SIGNAL(updateProgress(int)), w, SLOT(updateTheProgress(int)));
connect(this, SIGNAL(ProcessParticle()), this, SLOT(process()), Qt::QueuedConnection);
}
void Worker::process()
{
const int modNr = my_iterations / 1000;
QDateTime start = QDateTime::currentDateTime();
while (i < my_iterations) { //loop over iteration steps
[...] // <--- do my calculations
//handle progress
emit updateProgress(1);
if (QDateTime::currentDateTime() > start.addMSecs(300)) {
emit ProcessParticle();
++i; //ensure we return to the next iteration
return;
}
i++;
}
qDebug() << "FINISHED"; // <--- I can see this, so finished() should be emitted now...
emit finished();
}
（world.h 的一部分）
public slots:
void threadFinished();
void updateTheProgress(int value);
signals:
void updateProgress(int value);
（world.cpp 的一部分）
void World::threadFinished()
{
particleCounter++;
qDebug() << "particles finished: " << particleCounter; // <--- this is NEVER called !?!?
if (particleCounter == particles->size()) {
hasRun = true;
}
}
void World::updateTheProgress(int value)
{
globalProgress += value;
emit updateProgress(globalProgress);
}
void World::run(double deltaTau, double maxDist, int iterations)
{
globalProgress = 0;
particleCounter = 0;
hasRun = false;
for (int i = 0; i < particles->size(); i++) { //loop over all particles
QThread *thread = new QThread;
Worker *worker = new Worker(this, &(*particles)[i], bfields, deltaTau, maxDist, iterations);
worker->moveToThread(thread);
connect(thread, SIGNAL(started()), worker, SLOT(process()));
connect(worker, SIGNAL(finished()), thread, SLOT(quit()));
connect(worker, SIGNAL(finished()), thread, SLOT(deleteLater()));
connect(worker, SIGNAL(finished()), this, SLOT(threadFinished())); // <--- this connection SHOULD make sure, I count the finished threads
connect(thread, SIGNAL(finished()), worker, SLOT(deleteLater()));
thread->start();
}
}
（在 MainWindow.cpp 的某处）
progressBar->setValue(0);
progressBar->setMaximum(nrPart * iter);
connect(world, SIGNAL(updateProgress(int)), progressBar, SLOT(setValue(int)));
world->run(timeStep, dist, iter);
while (!world->hasBeenRunning()) {} //wait for all threads to finish
正如我在上面的代码中标记的那样，当线程完成时我永远不会收到通知，并且我最终在 MainWindow 中陷入无限循环。World <-> Worker 连接还有问题吗？