multithreading

问题 I would like to experiment with multithreading with c++. I am using the MinGW g++ compiler (version 8.2.0) on Windows 10. When I try to use the builtin thread library with c++ using the code I got directly from a website, I get the error: main.cpp:34:5: error: 'thread' was not declared in this scope thread th1(foo, 3); ^~~~~~ main.cpp:34:5: note: 'std::thread' is defined in header ''; did you forget to '#include '? main.cpp:5:1: +#include using namespace std; main.cpp:34:5: thread th1(foo, 3)

问题 So basically I am using the windows api to create an emty window and then I use OpenGL to draw to that window from different threads. I managed to do this just with one thread , but getting and dispatching system messages so that the window is usable was slowing down the frame rate I was able to get, so I'm trying to get another thread to do that in parallel while I draw in the main thread. To do this I have a second thread which creates an empty window and enters an infinite loop to handle

问题 To my understanding, there are the 3 ways of doing IO in Scala, which I will try to express in pesudo code. First , synchronous & blocking: val syncAndBlocking: HttpResponse = someHttpClient.get("foo.com") Here the main thread is just idle until the response is back.. Second , async but still blocking: val asyncButBlocking: Future[HttpResponse] = Future { someHttpClient.get("bar.com") } To my understanding, here the main thread is free (as Future executes on a separate thread) but that

问题 How do I create a named event object in C# so that I can wait on it in separate C++ process? My simplified C# code of process A: EventWaitHandle evt = new EventWaitHandle(false, EventResetMode.AutoReset, "eventName"); EventWaitHandle.SignalAndWait(evt , <other event>); And simplified C++ code of process B: HANDLE hEvt = OpenEvent( EVENT_MODIFY_STATE | SYNCHRONIZE, // access FALSE, // do not inherit handle TEXT("eventName") ); if (hEvt == NULL) { printf("CreateEvent failed (%d)\n",

问题 Why if I have two conditions while both returns the right type in a function as it should be, I am getting an alarm. control reaches end of non-void function [-Wreturn-type] bool EtherTrafGen::isGenerator() { if (multipacket) return par("destAddresses").stringValue()[0]; else if (!multipacket) return par("destAddress").stringValue()[0]; } What is the way to correct such an alarm? 回答1: Even though control can never reach bool EtherTrafGen::isGenerator() { if (multipacket) return par(

问题 I know there are similar questions like Here And Here, I looked them all, but they seems not work for me. I have a thread: private void Sample() { Thread t = new Thread(new ThreadStart(Sample_Thread)); t.SetApartmentState(ApartmentState.STA); t.Start(); } In the Sample_Thread, I previously called MessageBox which works fine. private void Sample_Thread() { try{ ... } catch(Exception e) { MessageBox.Show("SampleText"); } } Now I try to call ModernDialog instead of MessageBox , it gives me error

问题 What is the differene between concurrency and multithreading? Is concurrency only possible in multicore cpu? can anybody explain it with an example? 回答1: What is the differene between concurrency and multithreading? Concurrency describes the way in which processes run. They are either sequential (one after another), concurrent (able to make progress "at the same time" although not necessarily at the same instant), or parallel (they happen simultaneously). Multi-threading is a technique which

问题 Consider the following example taken from Wikipedia, slightly adapted, where the steps of the program correspond to individual processor instructions: x = 0; f = 0; Thread #1: while (f == 0); print x; Thread #2: x = 42; f = 1; I'm aware that the print statement might print different values (42 or 0) when the threads are running on two different physical cores/processors due to the out-of-order execution. However I don't understand why this is not a problem on a single core machine, with those

问题 I'm reading 'Fluent Python' by 'Luciano Ramalho' over and over, but I couldn't understand asyncio.sleep's behavior inside asyncio. Book says at one part: Never use time.sleep in asyncio coroutines unless you want to block the main thread, therefore freezing the event loop and probably the whole application as well. (...) it should yield from asyncio.sleep(DELAY). On the other part: Every Blocking I/O function in the Python standard library releases the GIL (...) The time.sleep() function also

问题 Consider the following code: List<int> list = new List<int>(); IEnumerable<int> enumerable = list; IEnumerator<int> enumerator = enumerable.GetEnumerator(); list.Add(1); bool any = enumerator.MoveNext(); At runtime, the last line throws an: InvalidOperationException: Collection was modified; enumeration operation may not execute. I understand the need for IEnumerators to throw 'Collection was modified' exceptions when the IEnumerable changes, but I don't understand this: Why does the