c++ - 当主线程显然未被阻塞时，QProgressDialog卡住

Question

我正在开发一个在耗时的计算过程中使用 QProgressDialog 的项目。为了不阻塞主UI线程，将执行计算的类移动到新的 QThread ，并使用通过 Qt::AutoConnection ( QObject::connect 的默认选项)连接的开始和结束信号与主线程同步。我的问题是QProgressDialog有时会冻结，就像在this视频中看到的一样(还附带了gif版本，但它不如视频清晰):

在此动画中，您可以看到启动项目后进度条如何卡在Second check上。应用程序将保持这种状态，直到鼠标再次输入QProgressDialog为止。这只会最终发生，如果将鼠标移到其他窗口上，则更容易发生。而且，它永远不会在同一阶段发生。
该软件的主要部分由StateMachine组成，该代码位于主线程中，并继承QObject并与其余小部件(在本例中为QProgressDialog)交互:
state_machine.h

#pragma once
#include <QObject>

class StateMachine : public QObject
{
  Q_OBJECT
public:
  static StateMachine* open(QThread* worker_thread, QWidget* parent);

signals:

  void finished();
  void datasetOpened();
  void requestCloseDataset();
  void errorMessage(QString text);

  void progressShow();

  void progressHide();

  void progressText(QString text);

  void requestProcess1();
  void requestProcess2();
  void requestProcess3();
  void requestProcess4();
protected slots:

  void process1Done();

  void process2Done();

  void process3Done();

  void process4Done();

protected:
  StateMachine(QThread* worker_thread, QWidget* parent = nullptr);
};

state_machine.cpp

#include "state_machine.h"

#include <QWidget>

#include "progress_dialog.h"
#include "state_machine_worker.h"

StateMachine *StateMachine::open(QThread *worker_thread, QWidget *parent)
{
  return new StateMachine(worker_thread, parent);
}

StateMachine::StateMachine(QThread *worker_thread, QWidget *parent) : QObject(parent)
{
  // Connect
  connect(this, &StateMachine::finished, this, &QObject::deleteLater);

  // Create worker
  StateMachineWorker *worker = new StateMachineWorker();
  worker->moveToThread(worker_thread);
  connect(this, &StateMachine::finished, worker, &QObject::deleteLater);
  /// Dataset file license
  connect(this, &StateMachine::requestProcess1, worker, &StateMachineWorker::process1);
  connect(worker, &StateMachineWorker::process1Done, this, &StateMachine::process1Done);
  /// Sonar list
  connect(this, &StateMachine::requestProcess2, worker, &StateMachineWorker::process2);
  connect(worker, &StateMachineWorker::process2Done, this, &StateMachine::process2Done);
  /// Sonar limit
  connect(this, &StateMachine::requestProcess3, worker, &StateMachineWorker::process3);
  connect(worker, &StateMachineWorker::process3Done, this, &StateMachine::process3Done);
  /// Dataset initialize
  connect(this, &StateMachine::requestProcess4, worker, &StateMachineWorker::process4);
  connect(worker, &StateMachineWorker::process4Done, this, &StateMachine::process4Done);

  // Create progress
  ProgressDialog *progress = ProgressDialog::create("OpenProject", "", "", 0, 0, parent, Qt::ApplicationModal);
  connect(this, &StateMachine::progressHide, progress, &QWidget::hide);
  connect(this, &StateMachine::progressShow, progress, &QWidget::show);
  connect(this, &StateMachine::finished, progress, &QWidget::hide);
  connect(this, &StateMachine::progressText, progress, &ProgressDialog::setLabelText);
  connect(this, &StateMachine::finished, progress, &QObject::deleteLater);

  // Check dataset file license
  emit progressText("First check");
  emit progressShow();
  emit requestProcess1();
}

void StateMachine::process1Done()
{
  emit progressText("Second check");
  emit requestProcess2();
}

void StateMachine::process2Done()
{
  emit progressText("Third check");
  emit requestProcess3();
}

void StateMachine::process3Done()
{
  emit progressText("Fourth check");
  emit requestProcess4();
}

void StateMachine::process4Done()
{
  emit progressHide();
  emit requestCloseDataset();
  emit datasetOpened();
  emit finished();
}

驻留在辅助线程中并与StateMachineWorker交互并执行线程阻塞过程的StateMachine。
state_machine_worker.h

#pragma once
#include <QObject>

class StateMachineWorker : public QObject
{
  Q_OBJECT
public:
  StateMachineWorker(QObject* parent = nullptr);

signals:

  void process1Done();

  void process2Done();

  void process3Done();

  void process4Done();

public slots:
  void process1();

  void process2();

  void process3();

  void process4();
};

state_machine_worker.cpp

#include "state_machine_worker.h"

#include <thread>

StateMachineWorker::StateMachineWorker(QObject *parent) : QObject(parent)
{
}

void StateMachineWorker::process1()
{
  std::this_thread::sleep_for(std::chrono::seconds(2));
  emit process1Done();
}

void StateMachineWorker::process2()
{
  std::this_thread::sleep_for(std::chrono::seconds(2));
  emit process2Done();
}

void StateMachineWorker::process3()
{
  std::this_thread::sleep_for(std::chrono::seconds(2));
  emit process3Done();
}

void StateMachineWorker::process4()
{
  std::this_thread::sleep_for(std::chrono::seconds(2));
  emit process4Done();
}

整个示例可以在here中找到。如您所见，工作器被移至线程以避免阻塞主UI线程。但是，从上一个视频中可以看出，无论主线程是否被阻止(或者至少我认为它未被阻止)，GUI都将变得无响应。
您对我在做什么错有任何想法吗？如何使进度对话框不冻结？如果我将QProgressDialog设置为Qt::NonModal而不是Qt::ApplicationModal，问题就消失了，但是我想阻止其他小部件的输入，因此不能更改它。
这仅在Windows上发生，并且已经在Windows 10，MSVC 19.26.28806.0和Qt版本5.14.2中进行了测试。在具有g++ 7和Qt 5.9.5的Ubuntu中，这不会发生。
PS:我知道StateMachine和StateMacineWorker只是一个对象，它驻留在辅助线程中并通过信号/插槽直接与主线程小部件交互，而不是让StateMachine驻留在主线程中并与工作人员交互，但是这不是这个问题的主要关注点。

Answer 1

问题显然是Qt中的一些错误。在Windows中使用Qt 5.15.0时，问题消失了。