线程化此方法会产生段错误，为什么? [英] threading this method produces a segfault, why?

问题描述

因此，即时通讯使用GLFW，并且在我的主要方法中调用时，以下方法可以正常工作

So im using GLFW and the following method works when called in my main method

void Display::run() {
    while (!glfwWindowShouldClose(window))
    {
        /* Render here */



        /* Swap Buffers And Poll */
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
}

但是当我尝试在单独的线程上运行它时，我会遇到段错误

but when i try to run it on a separate thread i get a segfault

std::thread t1(&Display::run, this);

有什么想法吗?询问是否需要更多代码

any ideas? ask if you want any more of the code

main.cpp

#include "src/support/Display.h"

int main() {
    Display* d;
    d->start();
    return 0;
}

Display.h

Display.h

#include <GLFW/glfw3.h>
#include <exception>
#include <thread>


class Display {

private:
    GLFWwindow* window;
    std::thread* displayThread;

    void run();

public:
    Display();
    void start();
    void close();
};

/* Exceptions */
struct GLFWNotInitilizedException : public std::exception
{
    const char * what () const throw ()
    {
        return "ERR: Could Not Initialize GLFW";
    }
};

struct WindowNotCreatedException : public std::exception
{
    const char * what () const throw ()
    {
        return "ERR: Could Not Create Window";
    }
};

Display.cpp

Display.cpp

#include "Display.h"

Display::Display() {
    //init glfw
    if (!glfwInit())
        throw GLFWNotInitilizedException();

    //create window and its context
    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        throw WindowNotCreatedException();
    }

    //make windows context current
    glfwMakeContextCurrent(window);

    //run(); //this works instead of calling start() which puts run() into a thread

}

/* begins the rendering of the display window contents in seperate thread */
void Display::start() {
    std::thread t1(&Display::run, this);
    displayThread = &t1;
}

/* renders contents of display window */
void Display::run() {
    while (!glfwWindowShouldClose(window)) //seg fault is output here
    {
        /* Render here */



        /* Swap Buffers And Poll */
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
}


/* to be used when closing display window */
void Display::close() {
    glfwSetWindowShouldClose(window, true);
    displayThread->join();
    glfwDestroyWindow(window);
}

推荐答案

Display* d;

您尚未在此处创建对象，只是未初始化的指针.

You haven't created an object here, just an uninitialised pointer.

d->start();

这将调用不存在的对象上的成员.当它尝试访问run()函数中的任何成员时，它只是访问垃圾，因为没有对象.

This calls a member on a nonexistent object. When it tries to access any members in the run() function it just accesses garbage because there is no object.

您可能想要创建一个像这样的对象:

You probably want to create an object like this:

Display d;
d.start();

此外，您的启动函数将终止程序，因为您在销毁线程之前不加入该线程.在尝试使用此类线程和指针之前，您应该了解C ++对象生存期的基础.

Also your start function will terminate the program because you don't join the thread before it is destroyed. You should learn the basics of C++ object lifetime before trying to use threads and pointers like this.

停止使用指针，直到您了解基本知识为止. displayThread应该是实际的std::thread，而不仅仅是指向超出范围的某些std::thread的指针.

Stop using pointers until you understand the basics. displayThread should be an actual std::thread not just a pointer to some std::thread that goes out of scope.

然后您可以做:

void Display::start() {
    displayThread = std::thread(&Display::run, this);
}

请确保在销毁displayThread.join()之前调用它，例如在Display析构函数中.

Make sure you call displayThread.join() before it is destroyed, e.g in the Display destructor.

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