mutex

问题 I tried to use Mutex module, such as Mutex.create(), but compiler says Unbound module Mutex. Does it require some special namespace? Thanks 回答1: For toplevel : ocaml -I +threads # #load "unix.cma";; # #load "threads.cma";; # Mutex.create ();; - : Mutex.t = <abstr> For ocamlc : ocamlc -thread unix.cma threads.cma src.ml For ocamlopt : ocamlopt -thread unix.cmxa threads.cmxa src.ml For findlib : ocamlfind ocamlc -thread -package threads -linkpkg src.ml 来源： https://stackoverflow.com/questions

问题 I have a Windows Forms application with C# code as shown below (targeting .NET framework 4). On my developer workstation, this code works to prevent me from launching multiple instances of the program. However, QA has a Citrix test environment where each user is still able to launch multiple instances. What can be done to prevent a given user from running multiple instances in Citrix? [STAThread] static void Main(string[] args) { bool isFirstInstance; Mutex m = new Mutex(true, "[App name goes

问题 Supposed I have a class that represent some data structure called foo: class foo{ public: foo(){ attr01 = 0; } void f(){ attr01 += 5; } private: int attr01; }; class fooSingleThreadUserClass{ void usefoo(){ fooAttr.f(); } foo fooAttr; } Now supposed later in software construction, I found out that I need multithreading. Should I add the mutex in foo? class foo{ public: foo(){ attr01 = 0; } void f(){ attr01Mutex.lock(); attr01 += 5; attr01Mutex.unlock(); } private: int attr01; std::mutex

问题 i am facing a deadlock in one of my c application(its a big code) and I was able to debug down the stage where I printed a mutex. It looks like below - {__data = {__lock = 2, __count = 0, __owner = 15805, __nusers = 1, __kind = 0, __spins = 0, __list = {__prev = 0x0, __next = 0x0} }, __size = "\002\000\000\000\000\000\000\000½=\000\000\001", '\0' <repeats 26 times>, __align = 2 } Now i could understand that __owner is thread id of thread holding this mutex, same thread ends up in deadlock for

问题 I've made this question: PHP mutual exclusion (mutex) As said there, I want several sources to send their stats once in a while, and these stats will be showed at the website's main page. My problem is that I want this to be done in an atomic manner, so no update of the stats will overlap another one running in the background. Now, I came up with this solution and I want you PHP experts to judge it. stats.php <?php define("my_counter", 12); ?> index.php <?php include "stats.php"; echo

问题 I have a set of methods that all synchronize to the class object (can't use self, because multiple instances of this object could be used in multiple threads). Some of those methods call other methods in the class that also synchronize on the class object. Somehow this works and does not cause the deadlock I would expect it to. I would assume that testA would be blocked from running because testB already has a lock on the class object, but this apparently isn't the case. Is it something

问题 If I call CloseHandle on a mutex before a thread has finished with the mutex, and hence, hasn't yet called ReleaseMutex, what is the expected behaviour? 回答1: The most serious consequence is a thread that's waiting for the mutex getting unblocked. The WaitXxx call returns WAIT_ABANDONED. At which point it would be a really good idea to call TerminateProcess because you have no idea what the hell just happened. 回答2: CloseHandle() immediately destroys the handle that is passed to it.

问题 The recommended way to use a mutex for locking a critical region of code is via RAII, i.e. mutex_type mutex; { // start of critical region std::lock_guard<mutex_type> lock(mutex); // first statement in critical region // ... do critical stuff, may throw an exception } // end of critical region so that when an exception is thrown within the critical region, the mutex will still be unlocked (by the destructor of std::lock_guard ). However, this way the members mutex::lock() and mutex::unlock()

问题 What's the difference between the two? If I do Mutex.Close() instead of Mutex.Release() when shutting down my app, what would be the side effect? 回答1: ReleaseMutex is used to allow another thread to obtain the mutex. It should only be called if you have acquired the mutex (called WaitOne and acquired it or acquired through the constructor). Important Note ReleaseMutex will throw an exception if you have not acquired the mutex. Close is used to clean up the resources that have been allocated

问题 I want to switch from CreatMutex to boost::interprocess::named_mutex to limit my application to a single instance. Both methods works when the application runs and ends just fine. However, the lock is not released when the application crashes and using boost::interprocess::named_mutex . I could resolve that issue by using two name_mutex but I don't really understand the issue. Why is the lock for boost::interprocess::named_mutex not released when the application crashes but it is release with