Near the beginning of this clip from C++ And Beyond, I heard something about problems with std::async . I have two questions: For a junior developer, is there a set of rules for what to do and what to avoid when using std::async ? What are the problems presented in this video? Are they related to this article? There are several issues: std::async without a launch policy lets the runtime
从C ++ And Beyond开始，我听到了有关std::async问题。 我有两个问题： 对于初级开发人员，在使用std::async时，有什么规则可以避免？ 此视频中出现了哪些问题？ 他们是否与这篇文章有关？ 有几个问题： 没有启动策略的std::async允许运行时库选择是启动一个新线程还是在将来调用get()或wait()的线程中运行任务。 正如Herb所说，这种情况很可能要使用。 问题在于，这会让它向运行时库的QoI开放，以便正确地获取线程
I have global vaiable in a below thread (bool allow) which restrict client to wait (by assign allow=false) till it is completed. After completed allow =true bool allow =true; static void * mythread(void *arg) { /* here is Lock mutex code */ allow =false;(**non atomic**) system(command); allow =true; /* here is Unlock Mutex code */ } if(allow) { // validate thread output } else
我有一个全局变量在下面的线程（布尔允许）限制客户端等待（通过分配允许= false），直到它完成。 完成后allow = true bool allow =true; static void * mythread(void *arg) { /* here is Lock mutex code */ allow =false;(**non atomic**) system(command); allow =true; /* here is Unlock Mutex code */ } if(allow) { // validate thread output } else { // wait } 我担心的是我应该使用std :: atomi
I have an application where a thread calls SetEvent and another thread waits for that event. However, CreateEvent was never called. The SetEven returns false (ERROR_INVALID_HANDLE), and the WaitForSingleObject returns WAIT_FAILED Yesterday, we commit something apparently not related : two lines of code in the .rc removing buttons from a toolbar. Suddently, on realease-XP-32 the WaitForSing
我有一个应用程序，其中一个线程调用SetEvent，另一个线程等待该事件。 但是，CreateEvent从未被调用过。 SetEven返回false（ERROR_INVALID_HANDLE），WaitForSingleObject返回WAIT_FAILED 昨天，我们提交了一些显然不相关的东西：.rc从工具栏中删除按钮的两行代码。 突然，在realease-XP-32上， WaitForSingleObject返回WAIT_TIMEOUT 。 但我想知道： 1-为什么在资源中提交（显然不相关）确实改变了WaitForSingleObj
I created two programs in C (producer and consumer) which send messages the one to each other (using CreateEvent, SetEvent and WaitForSingleObject) I implement one thread for each program to manages this messages using WaitForSingleObject(myEvent, INFINITE) waiting for a message I put the WaitForSingleObject in looping to repeat and obtain many messages in time. This works fine in the first
我在C（生产者和消费者）中创建了两个程序，它们互相发送消息（使用CreateEvent，SetEvent和WaitForSingleObject） 我为每个程序实现一个线程来使用WaitForSingleObject（myEvent，INFINITE）等待消息来管理这些消息 我把WaitForSingleObject放入循环中，以便及时重复并获取许多消息。 这在第一次工作正常，但其他时候WaitForSingleObject不等待消息，左代码运行在不定式循环中（包括WaitForSingleObject） 我测试删除两
I have two threads that use an event for synchronization. In each thread they use the same call: ::CreateEvent( NULL,TRUE,FALSE,tcEventName ) The producer thread is the one that makes the call first, while the consumer thread makes the call last, so it's technically opening, not creating the event... I assume. But, when SetEvent is called in the producer thread, the same event never gets
我有两个线程使用事件进行同步。 在每个线程中，他们使用相同的调用： ::CreateEvent( NULL,TRUE,FALSE,tcEventName ) 生产者线程是首先进行调用的线程，而消费者线程使得调用最后一次，所以它在技术上是开放的，而不是创建事件......我假设。 但是，当在生产者线程中调用SetEvent时，相同的事件永远不会在消费者线程中触发（我正在使用WaitForMultipleObjects（）） 有没有一种工具可以告诉我事件是否真正被正确触发。
I have an app, In which I am decoding video frames coming from ip camera, but the method avcodec_decode_video2(m_pCodecCtx, m_pFrame, &consumed_bytes, &avpkt); present in avcodec.h generating bad_access, I can't figure out what is wrong. This app was working fine with old libraries FFMpeg, but by apple policy, in order to publish app it support arm64, so I updated my libraries to s
我有一个应用程序，其中我解码来自IP摄像头的视频帧，但方法avcodec_decode_video2(m_pCodecCtx, m_pFrame, &consumed_bytes, &avpkt); 目前在avcodec.h生成bad_access，我无法弄清楚什么是错的。 这个应用程序与旧库FFMpeg工作正常，但通过苹果政策，为了发布它支持arm64的应用程序，所以我更新了我的库以支持arm64，之后发生了此问题。 这是截图 虽然bad_access应用程序正在生成以下日志： [h264 @ 0x1071400]
Update 3 : After understanding what "memory order" is, I know the problem is totally not related to compiler. And yes, because my CPU architecture is Intel x86, no matter what code I write, the memory order effect will never happen . Update 2 : I check the disassembly code. However, I find no matter how I add code, the x.store always prior to y.store. The problem should come
更新3 ： 在了解了“内存顺序”之后，我知道问题与编译器完全无关。 是的，因为我的CPU架构是Intel x86， 无论我写什么代码，内存顺序效果都不会发生 。 更新2 ： 我检查反汇编代码。 然而，我发现无论如何添加代码，x.store总是在y.store之前。 问题应该来自编译器（不重新排序这些代码）而不是CPU（据我所知）。 更新 ： 看完评论后，似乎我不得不借用CPU为alpha，arm或ppc的机器。 有人知道我可以在哪里使用这
I've a thread that read datas class MyThread: QThread { ... } void MyThread::run () { uint8_t* buffer; // in my real code, it's a ring, so there is not read during write // ... while (true) { if (isInterruptionRequested()) return; USB_READ(buffer); emit newData(buffer); } } In my UI Class I have: connect(this, &UIClass::newData, m_thread, &MyThread::
我有一个读取数据的线程 class MyThread: QThread { ... } void MyThread::run () { uint8_t* buffer; // in my real code, it's a ring, so there is not read during write // ... while (true) { if (isInterruptionRequested()) return; USB_READ(buffer); emit newData(buffer); } } 在我的UI类中，我有： connect(this, &UIClass::newData, m_thread, &MyThread::newData); //
I would like to use my own Thread implementation by wrapping the std::thread class from C++11 so I will be able handle exceptions like I want. Here is my wrap class: #include <Types.hpp> #include <thread> #include <exception> #include <functional> class Thread { private: std::exception_ptr exceptionPtr; std::thread thread; public: usi
我想通过从C ++ 11中包装std :: thread类来使用自己的Thread实现，这样我就可以处理像我想要的异常。 这是我的包装类： #include <Types.hpp> #include <thread> #include <exception> #include <functional> class Thread { private: std::exception_ptr exceptionPtr; std::thread thread; public: using Id = std::thread::id; using NativeHandleTy
I understand that about the only thing, a signal handler in ISO/C++11 is allowed to do is to read from or write to a lock free atomic variable or a volatile sig_atomic_t (I believe, POSIX is a little bit more permissive and allows to call a bunch of system functions). I was wondering, if there is any way, to wake up a thread that is waiting on a condition variable. Ie something like: #include
我明白关于唯一的事情，ISO / C ++ 11中的信号处理程序允许执行读取或写入锁定自由原子变量或volatile sig_atomic_t （我相信，POSIX是一个更宽容和允许调用一堆系统函数）。 我想知道，如果有什么办法，唤醒正在等待条件变量的线程。 即像是： #include <mutex> #include <atomic> #include <condition_variable> std::mutex mux; std::condition_variable cv; std::atomic_bool doWait{ true }; void