mutex

From sample example 4 of MSDN "Threading Tutorial" Following code errors out at the line commented with "---errors is here---". What is wrong? using System; using System.Threading; public class MutexSample { static Mutex gM1; static Mutex gM2; const int ITERS = 100; static AutoResetEvent Event1 = new AutoResetEvent(false); static AutoResetEvent Event2 = new AutoResetEvent(false); static AutoResetEvent Event3 = new AutoResetEvent(false); static AutoResetEvent Event4 = new AutoResetEvent(false); public static void Main(String[] args) { Console.WriteLine("Mutex Sample ..."); // Create Mutex

Borrowing Howard Hinnant's example and modifying it to use copy-and-swap, is this op= thread-safe? struct A { A() = default; A(A const &x); // Assume implements correct locking and copying. A& operator=(A x) { std::lock_guard<std::mutex> lock_data (_mut); using std::swap; swap(_data, x._data); return *this; } private: mutable std::mutex _mut; std::vector<double> _data; }; I believe this thread-safe (remember op='s parameter is passed by value), and the only problem I can find is the one swept under the rug: the copy ctor. However, it would be a rare class that allows copy-assignment but not

I read a few documents about Mutex and still the only Idea I have got is that it helps preventing threads from accessing a resource that is already being used by another resource. I got from Code snippet and executed which works fine: #include <windows.h> #include <process.h> #include <iostream> using namespace std; BOOL FunctionToWriteToDatabase(HANDLE hMutex) { DWORD dwWaitResult; // Request ownership of mutex. dwWaitResult = WaitForSingleObject( hMutex, // handle to mutex 5000L); // five-second time-out interval switch (dwWaitResult) { // The thread got mutex ownership. case WAIT_OBJECT_0:

I have a web application that needs to utilise an application cache to store data (due to the high overhead of obtaining that data ona request by request basis). See previous post at https://stackoverflow.com/a/16961962/236860 This approach seems to work well, but I am seeing the following occasional errors in the web site's error: System.ApplicationException: Object synchronization method was called from an unsynchronized block of code. at System.Threading.Mutex.ReleaseMutex() at InboxInsight.Web.Web_Controls.Twitter.TwitterFeed.GetTwitterData(HttpContext context) at InboxInsight.Web.Web

I have been reading different things on multithreading, C++, proper synchronization and locks to prevent race conditions. One question has not been answered for me, however: Is there a mutex required if I create an object in thread A, but use it exclusively in thread B afterwards? In other words, I know that I don't need a mutex to prevent race conditions - do I need a mutex to serve as a memory barrier (or other potential problems)? A very basic example to visualize what I mean struct Object { void do_stuff(); }; Object o; std::thread worker_thread([&o](){ while (alive) o.do_stuff(); }).join(