If you want to run code on many platforms, go for Posix Threads. They are available almost everywhere and are quite mature. On the other hand if you only use Linux/gcc std::thread is perfectly fine – it has a higher abstraction level, a really good interface and plays nicely with other C++11 classes. The C++11 … Read more
To expand on Michael’s comment. static simply means not associated with an instance of the containing class. volatile simply means that the value may be changed by other threads without warning. So your question boils down to “can a field not associated with an instance of the containing class be changed by another thread without … Read more
As stated, your loop will not hog the CPU. But beware: Windows is not a real-time OS, so you will not get 1000 wakes per second from Thread.Sleep(1). If you haven’t used timeBeginPeriod to set your minimum resolution you’ll wake about every 15 ms. Even after you’ve set the minimum resolution to 1 ms, you’ll … Read more
Since std::get has no explicit statements in the specification about its data race properties, we fall back to the default behavior defined in [res.on.data.races]. Specifically, paragraphs 2 and 3 tell the story: A C++ standard library function shall not directly or indirectly access objects (1.10) accessible by threads other than the current thread unless the … Read more
You’re dealing with sleep times termed in tens of seconds. The possible savings by changing your sleep option here is likely nanoseconds or microseconds. I’d prefer the latter style every time, but if you have the former and it’s going to cost you a lot to change it, “improving performance” isn’t a particularly good justification. … Read more
tl;dr I think you are running into GC-related behavior, where threads are being put in waiting state to allow for garbage collection. I do not have the whole truth but I hope to provide some pieces of insight. First thing to realize is that the number in brackets, [0x00007fe64df9a000], is not the address of a … Read more
The standard allows for this behavior, although it doesn’t guarantee it. From 3.7.2/2 [basic.stc.thread]: A variable with thread storage duration shall be initialized before its first odr-use (3.2) and, if constructed, shall be destroyed on thread exit. It’s also possible that the objects are constructed at some other time (e.g. on program startup), as “before … Read more
You are thinking in terms of sequential consistency, the strongest (and default) memory order. If this memory order is used, all accesses to atomic variables constitute a total order, and the assertion indeed cannot be triggered. However, in this program, a weaker memory order is used (release stores and acquire loads). This means, by definition … Read more
No, you should be doing your calculations in a separate thread. As you already mentioned, there is a work-around available in QCoreApplication::processEvents(), but it sounds like you’re unable to make that work for you. If you don’t want to have to do all the work of setting up a QThread and moving all your code, … Read more
It’s something introduced in C99 which lets the compiler know that the pointer passed in there isn’t pointing to the same place as any other pointers in the arguments. If you give this hint to the compiler, it can do some more aggressive optimizations without breaking code. As an example, consider this function: int add(int … Read more