Mutex解锁失败了

Question

我正在玩一些套接字,线程和互斥.我的问题涉及线程和互斥体:

int ConnectionHandler::addNewSocket(){

    this->connectionList_mutex.lock();
    std::cout << "test1" << std::endl;
    this->connectionList_mutex.unlock();

    return 0;
}

int ConnectionHandler::main(){
    while(true){
        this->connectionList_mutex.lock();
        std::cout << "test2" << std::endl;
        this->connectionList_mutex.unlock();
    }

}`

main函数在一个线程中运行,而addNewSocket由另一个线程调用.问题是,当addNewSocket被调用一次(由第二个线程)时,线程1(main)的下一个解锁将失败并出现奇怪的"信号SIGABRT".我现在已经工作了两天,但遗憾的是我无法修复它.我希望你能帮助我.

编辑:ConnectionHandler是一个类,具有connectionList_mutex作为成员.

编辑:有时我也会收到此错误:"断言失败:(ec == 0),函数解锁,文件/SourceCache/libcxx/libcxx-65.1/src/mutex.cpp,第44行." 但它随机发生.

编辑:这是整个类(减少到最小,应该在某种程度上独立于上下文,但是当我在连接客户端之后立即崩溃时崩溃,并且如果我在开始之后立即执行它会起作用:

class ConnectionHandler{
public:
    ConnectionHandler();
    int addNewSocket();
private:
    int main();
    static void start(void * pThis);

    std::mutex connectionList_mutex;
};

ConnectionHandler::ConnectionHandler(){
    std::thread t(&this->start, this);
    t.detach();
}
void ConnectionHandler::start(void * pThis){
    ConnectionHandler *handlerThis;
    handlerThis = (ConnectionHandler *)pThis;
    handlerThis->main();
}


int ConnectionHandler::addNewSocket(){

    this->connectionList_mutex.lock();
    std::cout << "test1" << std::endl;
    this->connectionList_mutex.unlock();

    return 0;
}

int ConnectionHandler::main(){
    while(true){
        this->connectionList_mutex.lock();
        std::cout << "test2" << std::endl;
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        this->connectionList_mutex.unlock();

    }

}

Answer 1

我的猜测是你的ConnectionHandler物体在某处被摧毁.此外,您已经ConnectionHandler::start以愚蠢的方式定义.

首先,ConnectionHandler::start应该这样定义:

void ConnectionHandler::start(ConnectionHandler * pThis){
    pThis->main();
}

C++ 11 ::std::thread类完全能够保留函数参数的类型,因此无需求助void *.

其次,添加以下代码:

void ConnectionHandler::~ConnectionHandler(){
    const void * const meptr = this;
    this->connectionList_mutex.lock();
    ::std::cout << "ConnectionHandler being destroyed at " << meptr << ::std::endl;
    this->connectionList_mutex.unlock();
}

并将构造函数更改为:

ConnectionHandler::ConnectionHandler(){
    const void * const meptr = this;
    ::std::cout << "ConnectionHandler being created at " << meptr << ::std::endl;
    std::thread t(&this->start, this);
    t.detach();
}

这将显示ConnectionHandler对象何时被销毁.我的猜测是,当你的分离线程仍在运行时,你的代码正在破坏它.

该meptr事情是因为operator <<有一个重载的void *打印出的指针值.this如果要创建多个ConnectionHandler对象,则打印出指针值将允许您匹配对构造函数和析构函数的调用.

编辑:既然事实证明我是对的,这里是我建议你写的游戏ConnectionHandler类:

#include <iostream>
#include <atomic>
#include <thread>
#include <chrono>
#include <mutex>

class ConnectionHandler {
 public:
   ConnectionHandler();
   ~ConnectionHandler();
   ConnectionHandler(const ConnectionHandler &) = delete;
   const ConnectionHandler &operator =(const ConnectionHandler &) = delete;

   int addNewSocket();

 private:
   int main();
   static void start(ConnectionHandler * pThis);

   ::std::mutex connectionList_mutex;
   volatile ::std::atomic_bool thread_shutdown;
   ::std::thread thread;
};

ConnectionHandler::ConnectionHandler()
     : thread_shutdown(false), thread(&this->start, this)
{
}

ConnectionHandler::~ConnectionHandler()
{
   thread_shutdown.store(true);
   thread.join();
}

void ConnectionHandler::start(ConnectionHandler * pThis){
   pThis->main();
}

int ConnectionHandler::addNewSocket(){
   ::std::lock_guard< ::std::mutex> lock(connectionList_mutex);
   ::std::cout << "test1" << ::std::endl;

   return 0;
}

int ConnectionHandler::main(){
   while(!thread_shutdown.load()){
      ::std::lock_guard< ::std::mutex> lock(connectionList_mutex);
      ::std::cout << "test2" << ::std::endl;
      ::std::this_thread::sleep_for(::std::chrono::milliseconds(100));

   }
   return 0;
}