Invalid parameter passed to C runtime function

Hi everybody,

have some trouble with Runtime library on step run of application (compiling was successful, build too) but when I press Start have a crash with this tags:

Quote:

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Invalid parameter passed to C runtime function.
Invalid parameter passed to C runtime function.
terminate called after throwing an instance of ‘std::system_error’ what(): Invalid argument
QObject::killTimers: timers cannot be stopped from another thread
Use: Qt 5.3 win MinGW 4.8 ×32 but run on x64 system, maybe problem here but i’m not sure
or because I try to combine c++11 code with Qt, but not sure too, because Qt traslate all it code to C++…

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cannibals.h

Code:

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#ifndef CANNIBALS_H
#define CANNIBALS_H
#include <thread>
#include <mutex>
#include <time.h>
#include <windows.h>
#define M 100
 
#include <QObject>
 
class Cannibals : public QObject
{
    Q_OBJECT
public:
    explicit Cannibals(QObject *parent = 0);
    void Dinner_a(int);
 
private:
    void Cooking();
    void Dinner();
    std::thread Cook;
    std::mutex eating;
    int food=10;
 
signals:
    void NumberChanged(int);
 
public slots:
 
};
 
#endif // CANNIBALS_H

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cannibals.cpp

Code:

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#include "cannibals.h"
 
Cannibals::Cannibals(QObject *parent) :
    QObject(parent)
{
}
 
void Cannibals::Cooking()
{
     food=M;
}
 
void Cannibals::Dinner_a(int z)
    {
        eating.lock();
        for(int i=0; i<z;i++){
        Dinner();}
        eating.unlock();
    }
 
void Cannibals::Dinner()
{
    if(food!=0){
    emit NumberChanged(food);
    --food;}
    else
    Cook = std::thread(&Cannibals::Cooking, this);
    Cook.join();
 
    Sleep(rand() 00);
}

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mainwindow.h

Code:

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#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include "cannibals.h"
#include <ui_mainwindow.h>
#include <QMainWindow>
#include <thread>
#define N 20
#define M 100
#define P (M/N)
 
namespace Ui {
class MainWindow;}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
     Cannibals *Foo;
     std::thread Cannibal[N];
 
private slots:
    void on_pushButton_clicked();
 
private:
    Ui::MainWindow *ui;
 
public slots:
    void OnNumberChanged (int);
};
 
#endif // MAINWINDOW_H

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mainwindow.cpp

Code:

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#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    Foo = new Cannibals();
    connect(Foo,SIGNAL(NumberChanged(int)),this,SLOT(OnNumberChanged(int)));
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::on_pushButton_clicked()
{
 
            for(int i=0;i<N;i++)
                    {
                       Cannibal[i] = std::thread(&Cannibals::Dinner_a, Foo, P);
                    }
 
            for(int i=0;i<N;i++)
            {
             Cannibal[i].join();
            }
}
 
void MainWindow::OnNumberChanged(int Num)
{
    ui->listWidget->clear();
    ui->pushButton->setEnabled(false);
    ui->listWidget->addItem(QString(Num) + " cannibal ate");
}

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Is this some kind of academic exercise or does the example have any practical goal? What is the point of all those threads?

Quote:

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Originally Posted by wysota

Is this some kind of academic exercise or does the example have any practical goal? What is the point of all those threads?

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Yes, this is exercise to practice in multithreading, but GUI is required condition and I chose Qt. About point: 20 threads - children and 1 thread - mother, children eat plumps, and when bowl is empty call mom to fill it. Amount of children and plumps is variables...

The Qt signal/slot code might not recognize the non-Qt thread correctly and chose to handle your connect() as a DirectConnection instead of QueuedConnection.

Try it with explicitly specifying that

Code:

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connect(Foo,SIGNAL(NumberChanged(int)),this,SLOT(OnNumberChanged(int)), Qt::QueuedConnection);

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Cheers,
_

Attachment 10772

Quote:

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Originally Posted by anda_skoa

Code:

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connect(Foo,SIGNAL(NumberChanged(int)),this,SLOT(OnNumberChanged(int)), Qt::QueuedConnection);

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This is have no effect, add full project for tests.

Quote:

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Originally Posted by Satansoft

Yes, this is exercise to practice in multithreading, but GUI is required condition and I chose Qt. About point: 20 threads - children and 1 thread - mother, children eat plumps, and when bowl is empty call mom to fill it. Amount of children and plumps is variables...

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I think you overcomplicated the code. And shouldn't the producer be a thread living all the time just waiting for the consumers to tell it to start producing? Right now you start a thread only to set a variable and then the thread dies. With the architecture you have there is completely no benefit from having threads so I doubt this is what your professor had in mind.

Quote:

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Originally Posted by wysota

I think you overcomplicated the code. And shouldn't the producer be a thread living all the time just waiting for the consumers to tell it to start producing? Right now you start a thread only to set a variable and then the thread dies. With the architecture you have there is completely no benefit from having threads so I doubt this is what your professor had in mind.

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Perhaps and overcomplicated, but task must be solved. I chose C++11 methods by reason of transparency, have any ideas to solve it?

Quote:

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Originally Posted by Satansoft

Perhaps and overcomplicated, but task must be solved. I chose C++11 methods by reason of transparency, have any ideas to solve it?

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If it is your school task then we cannot interfere with it, we can only give you hints regarding the use of Qt. I can only suggest to divide your code into classes -- one for the producer, one for the consumer and one for management and user-interface. Then it should be much easier for you to comprehend what is where. If using std::thread is not an explicit requirement then you might want to switch to using QThread.