c++ - 当主线程显然未阻塞时，QProgressDialog 冻结

问题描述

我正在开发一个QProgressDialog在耗时的计算过程中使用 a 的项目。为了不阻塞主 UI 线程，执行计算的类被移动到一个新的类，并QThread使用连接的开始和结束信号与主线程同步Qt::AutoConnection，默认选项QObject::connect. 我的问题是QProgressDialog有时会在此视频中看到冻结（还附有 gif 版本，但不如视频清晰）：

在此动画中，您可以看到启动项目后，进度条如何卡在Second check. 并且应用程序保持这种状态，直到鼠标再次进入QProgressDialog. 这种情况最终会发生，如果您将鼠标移到其他窗口上，则更容易发生这种情况。而且它永远不会在同一阶段发生。

该软件的主要部分包括一个StateMachine存在于主线程中并继承QObject并与其余小部件交互的小部件（在本例中为QProgressDialog）：

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();
}

AStateMachineWorker存在于辅助线程中并与交互StateMachine并执行线程阻塞的进程。

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();
}

可以在此处找到整个示例。如您所见，worker 被移动到线程以避免阻塞主 UI 线程。但是，正如在上一个视频中看到的那样，无论主线程是否被阻塞（或者至少我认为它没有被阻塞），GUI 都会变得无响应。

你知道我做错了什么吗？如何使进度对话框不冻结？如果我将其设置QProgressDialog为Qt::NonModal而不是Qt::ApplicationModal问题消失，但我想阻止其他小部件的输入，那么改变它不是一个选项。

这只发生在 Windows 上，并且已经在 Windows 10、MSVC 19.26.28806.0 和 Qt 版本 5.14.2 上进行了测试。在带有 g++7 和 Qt 5.9.5 的 Ubuntu 中，它不会发生。

PS：我知道，StateMachine因为StateMacineWorker它可能只是一个存在于辅助线程中并通过信号/插槽直接与主线程小部件交互的对象，而不是StateMachine生活在主线程中并与工作者交互，但这不是这个问题的主要关注点。

标签： c++windowsqt

c++ - 当主线程显然未阻塞时，QProgressDialog 冻结

问题描述

解决方案

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