qtconcurrent

问题 When I have been trying to implement "parallel for" using QtConcurrent::map: QFuture<void> parForAsync(size_t n, std::function<void (size_t)> Op) { size_t nThreads = static_cast<size_t>(QThreadPool::globalInstance()->maxThreadCount()); size_t nn = n/nThreads + 1; using Sequence = QVector<std::function<void()>>; Sequence vFuns; for(size_t i = 0; i < n; i+=nn) { size_t firstIdx = i, lastIdx = i + nn > n ? n : i + nn; vFuns.push_back([=]()->void { for(size_t i = firstIdx; i < lastIdx; ++i) { Op

问题 Hi have need to do some socket communication from background, I used QtConcurrent::run to this, but giving me the warning. QObject: Cannot create children for a parent that is in a different thread. (Parent is MainWindow(0x7fff3e69f500), parent's thread is QThread(0x16f8070), current thread is QThread(0x17413d0) Here is the code, MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent),ui(new Ui::MainWindow){ ui->setupUi(this); QFuture<void> f2 = QtConcurrent::run(this,&MainWindow:

问题 Let's say I call QtConcurrent::run() which runs a function in a worker thread, and in that function I dynamically allocate several QObjects (for later use). Since they were created in the worker thread, their thread affinity should be that of the worker thread. However, once the worker thread terminates, the QObject thread affinity should no longer be valid. The question: Does Qt automatically move the QObjects into the parent thread, or are we responsible in moving them to a valid thread

问题 My project is to create a small program which demonstrates the work of a search engine: indexing and returning result for arbitrary queries. I've done the work with the indexer part and now I want to improve it with indexing multiple files at once. The MainWindow class is here: class MainWindow : public QMainWindow { Q_OBJECT ..... private: Indexer * indexer; QStringList fileList; .... void index(QStringList list); void add(const QString &filename); } This is the implementation of add ( add

问题 I create a QFuture that I want to use to parallelize calls to a member function. More precisely, I have a class solveParallel with .h : class solverParallel { public: solverParallelData(Manager* mgr_); virtual ~solverParallel(void); void runCompute(solveModel * model_); bool resultComput(); private: Manager *myMgr; QFuture<bool> myFutureCompute; }; where the methode runCompute() is creating the myFutureCompute member. .cpp looks like solveParallel::solveParallel(Manager* mgr_) :m_mgr(mgr_) {

问题 I have the shared library project with structure like this: library.pro: TEMPLATE = subdirs CONFIG += ordered SUBDIRS += libs plugins test_programs ... QT += concurrent ... # Those files contains pure interfaces (C++ abstract classes) # with no implementation, and some helper classes with inline implementation. # So there is no reason to create yet another subproject for them HEADERS += iface/IInterface1.h \ iface/IInterface2.h \ # IInterface2 needs QtConcurrent ... IInterface2.h: ...

问题 Could point at some code using QRunnable as an alternative to QtConcurrent: I can't find any QRunnable example in Qtdoc. Did you ever try QRunnable AND QtConcurrent for same application, and could you comment on the compared performance? 回答1: QRunnable is an interface. So rather than looking for "a QRunnable example" it would be better to look for (for instance) "a QThreadPool example", such as: http://doc.qt.io/qt-4.8/thread-basics.html#example-1-using-the-thread-pool If you read further on

问题 In my UI, I have a QCustomPlot and I have generatePlot function which uses from this QCustomPlot and runs in a new thread as follows: future = QtConcurrent::run(this, &MainWindow::generatePlot); In generatePlot function, I create QCPbars like this: QCPBars *bar = new QCPBars(customPlot->xAxis, customPlot->yAxis); But, I get this error : QObject: Cannot create children for a parent that is in a different thread. I think that's because the thread of customPlot is diffrenet from bar . How can I

问题 I'm currently trying to parallelize my code, therefore I'm using QtConcurrent::run and the problem is, run doesn't know which function to choose. Is there a way to use run with an overloaded function or do I have find some sort of workaround? 回答1: You can just static_cast the pointer to ensure there's no ambiguity in the process void hello(QString name) { qDebug() << "Hello" << name << "from" << QThread::currentThread(); } void hello(int age) { qDebug() << "Hello" << age << "from" << QThread:

问题 Platform: Win7 x64, MinGW-rubenvb (4.7.2-x64), Qt 4.8 Say I have few lengthy tasks (read population file, write population file, and run simulation) spawned using QConcurrent::run, as follow: void MainWindow::runLengthyJob() { /* some setup */ jobWatcher->setFuture(QConcurrent::run(theApp, &AppClass::lengthyJob)); // lengthyJob - can be readPop(), writePop(), runSim() } Usually those tasks take at least 15 seconds to finish (for simulation, it takes more than hours). To prevent crashing from