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copied!<p>My guess is that your <code>ConnectionHandler</code> object is being destroyed somewhere. Also, you have defined <code>ConnectionHandler::start</code> in a silly way.</p> <p>First, <code>ConnectionHandler::start</code> should be defined this way:</p> <pre><code>void ConnectionHandler::start(ConnectionHandler * pThis){ pThis->main(); } </code></pre> <p>The C++11 <code>::std::thread</code> class is perfectly capable of preserving the type of the function argument so there is no need to resort to <code>void *</code>.</p> <p>Secondly, add in this code:</p> <pre><code>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(); } </code></pre> <p>And change the constructor to read:</p> <pre><code>ConnectionHandler::ConnectionHandler(){ const void * const meptr = this; ::std::cout << "ConnectionHandler being created at " << meptr << ::std::endl; std::thread t(&this->start, this); t.detach(); } </code></pre> <p>This will show you when the <code>ConnectionHandler</code> object is being destroyed. And my guess is that your code is destroying it while your detached thread is still running.</p> <p>The <code>meptr</code> thing is because <code>operator <<</code> has an overload for <code>void *</code> that prints out the pointer value. Printing out the pointer value for <code>this</code> will allow you to match up calls to the constructor and destructor if you're creating multiple <code>ConnectionHandler</code> objects.</p> <p><em>Edit:</em> Since it turned out I was correct, here is how I would recommend you write the play ConnectionHandler class:</p> <pre><code>#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; } </code></pre>

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