multithreading

问题 Suppose I wanted to copy the contents of a device register into a variable that would be read by multiple threads. Is there a good general way of doing this? Here are examples of two possible methods of doing this: #include <atomic> volatile int * const Device_reg_ptr = reinterpret_cast<int *>(0x666); // This variable is read by multiple threads. std::atomic<int> device_reg_copy; // ... // Method 1 const_cast<volatile std::atomic<int> &>(device_reg_copy) .store(*Device_reg_ptr, std::memory

问题 I'm currently stuck on a problem with a timer. I've got a function that is started by a timer every x seconds. Now the function execution can sometimes take longer under different conditions. So I want the timer to rerun only when it has completed the function. How can I achieve this? 回答1: Right before it exits, your function could trigger an event. The event will be caught by another function, which will start the timer. 回答2: My advice would be to avoid using a Timer class for this. The

问题 context: there are distinctions between different telnet clients, and certainly a distinction from those clients to, for example, the Apache library. In this case, yes, using an actual telnet client for MUD's, where the servers can be quite finnicky, so that API's or sockets just won't work. How do I go about: Spawn a new Process for every piped command. Create Threads that read the output from one command and write it to the input of the next command. right now there's no output for: package

问题 context: there are distinctions between different telnet clients, and certainly a distinction from those clients to, for example, the Apache library. In this case, yes, using an actual telnet client for MUD's, where the servers can be quite finnicky, so that API's or sockets just won't work. How do I go about: Spawn a new Process for every piped command. Create Threads that read the output from one command and write it to the input of the next command. right now there's no output for: package

问题 I have the following code, which deadlocks on the commented lines. Basically f1 and f2 run as individual threads in the program. f1 expects i to be 1 and decrements it, notifying the cv. f2 expects i to be 0 and increments it, notifying the cv. I assume the deadlock occurs if f2 increments i to 1, calls cv.notify(), then f1 reads a stale value of i (which is 0) because there is no memory synchronization between the mutex and i and then waits and never gets woken up. Then f2 also enters a

问题 I have a simple piece of code driving me crazy for a while. I have posted this question some days ago asking create_task is not working with input . Now I have figured out something related to this. I am running event loop in a separate thread and pushing tasks in it. Very straight forward code. import asyncio import threading async def printer(message): print(f'[printer] {message}') def loop_runner(loop): loop.run_forever() if __name__ == '__main__': event_loop = asyncio.get_event_loop() t =

问题 I read the below program and answer in a blog. int x = 0; boolean bExit = false; Thread 1 (not synchronized) x = 1; bExit = true; Thread 2 (not synchronized) if (bExit == true) System.out.println("x=" + x); is it possible for Thread 2 to print “ x=0 ”? Ans : Yes ( reason : Every thread has their own copy of variables. ) how do you fix it? Ans : By using make both threads synchronized on a common mutex or make both variable volatile. My doubt is : If we are making the 2 variable as volatile

问题 I got this little code to test out Callable . However, I find it pretty confusing how the Compiler could know if the Lambda is for the Interface Callable or Runnable since both don't have any parameter in their function. IntelliJ, however, shows that the Lambda employs the code for a Callable. public class App { public static void main(String[] args) throws InterruptedException { ExecutorService executorService = Executors.newCachedThreadPool(); executorService.submit(() ->{ System.out

问题 I got this little code to test out Callable . However, I find it pretty confusing how the Compiler could know if the Lambda is for the Interface Callable or Runnable since both don't have any parameter in their function. IntelliJ, however, shows that the Lambda employs the code for a Callable. public class App { public static void main(String[] args) throws InterruptedException { ExecutorService executorService = Executors.newCachedThreadPool(); executorService.submit(() ->{ System.out

问题 I got this little code to test out Callable . However, I find it pretty confusing how the Compiler could know if the Lambda is for the Interface Callable or Runnable since both don't have any parameter in their function. IntelliJ, however, shows that the Lambda employs the code for a Callable. public class App { public static void main(String[] args) throws InterruptedException { ExecutorService executorService = Executors.newCachedThreadPool(); executorService.submit(() ->{ System.out