multithreading

问题 I'm making an application and I'm using a timer in that application to change label content in WPF C# .NET. In the timer's elapsed event I'm writing the following code lblTimer.Content = "hello"; but its throwing an InvalidOperationException and gives a message The calling thread cannot access this object because a different thread owns it. I'm using .NET framework 3.5 and WPF with C#. Please help me. Thanks in advance. 回答1: For .NET 4.0 it is much simpler to use a DispatcherTimer. The

问题 I would like to benefit from all the potential of parallel command on macOS (it seems there exists 2 versions, GNU and Ole Tange's version but I am not sure). With the following command: parallel -j8 find {} ::: * I will have a big performance if I am located in a directory containing 8 subdirectories. But if all these subdirectories have a small content except for only one, I will have only one thread which will work on the unique "big" directory. Is there a way to follow the parallelization

问题 I understand the purpose of joining a thread, I'm asking about resource use. My specific use-case here is that I have a long-running process that needs to spawn many threads, and during operation, checks if they have terminated and then cleans them up. The main thread waits on inotify events and spawns threads based on those, so it can't block on join() calls, because it needs to block on inotify calls. I know that with pthreads, for instance, not joining a terminated thread will cause a

问题 I'm trying to learn async programming in C++. In Python, we have await , with which we can resume a function from that point, but in C++ future waits for the results and halts the next line of code. What if we don't want to get the result, but instead continue to the next line of code? How can I do this? 回答1: You can use std::future::wait_for to check if the task has completed execution, e.g. : if (future.wait_for(100ms) == std::future_status::ready) { // Result is ready. } else { // Do

问题 I'm trying to learn async programming in C++. In Python, we have await , with which we can resume a function from that point, but in C++ future waits for the results and halts the next line of code. What if we don't want to get the result, but instead continue to the next line of code? How can I do this? 回答1: You can use std::future::wait_for to check if the task has completed execution, e.g. : if (future.wait_for(100ms) == std::future_status::ready) { // Result is ready. } else { // Do

问题 In old synchronized block, we used same object to synchronize on, also used wait and notify methods. So they can all refer to same lock. Makes sense. So when I use class ReentrantLock, why can't I also use same variable to call lock , unlock as well as await and signal ? Why do I need to make additional Condition variable? That is, why I need to do this: Lock lock = new ReentrantLock(); Condition condition = lock.newCondition(); void doSomething() { lock.lock(); //some code condition.await();

问题 I'm currently trying to have a function called every 10ms to acquire data from a sensor. Basically I was trigerring the callback from a gpio interupt but I changed my sensor and the one I'm currently using doesn't have a INT pin to drive the callback. So my goal is to have the same behaviour but with an internal interupt generated by a timer. I tried this from this topic import threading def work (): threading.Timer(0.25, work).start () print(time.time()) print "stackoverflow" work () But

问题 From multiple articles around the internet it's advised not to swallow InterruptedException . It makes much more sense to do it with thread pool executors something like this when I'm going to reuse the same thread. public static void main(String[] args) throws InterruptedException { ExecutorService executor = Executors.newSingleThreadExecutor(); Future<?> future = executor.submit(() -> { printNumbers(); // first call printNumbers(); // second call }); Thread.sleep(3_000); executor

问题 I am creating a thread using _beginthreadex function. The function address I am passing in it has an infinite while loop ( while(1) ) . I have the threadid and threadhandle . I can use TerminateThread(threadhandle,1); But it is dangerous. The safe way is to kill thread using _endthreadex but it can only be used from inside the thread, and I wanted to kill the thread from outside. So please suggest if there is a safe way to close,end or kill the thread safely from outside using threadid or

问题 I am creating a thread using _beginthreadex function. The function address I am passing in it has an infinite while loop ( while(1) ) . I have the threadid and threadhandle . I can use TerminateThread(threadhandle,1); But it is dangerous. The safe way is to kill thread using _endthreadex but it can only be used from inside the thread, and I wanted to kill the thread from outside. So please suggest if there is a safe way to close,end or kill the thread safely from outside using threadid or