Unexpected Output when Using std::atomic with Custom Structs in C++20
I've spent hours debugging this and I'm updating my dependencies and I am having trouble with using `std::atomic` on a custom struct in C++20. I have a struct that contains a few primitive data types and I need to ensure that the instances of this struct are thread-safe. Here’s the struct I am using: ```cpp struct Data { int id; double value; }; ``` I thought I could use `std::atomic<Data>` to ensure thread safety, so I implemented it like this: ```cpp #include <atomic> #include <thread> #include <iostream> std::atomic<Data> atomicData; void updateData(int newId, double newValue) { Data newData = {newId, newValue}; atomicData.store(newData); } void printData() { Data currentData = atomicData.load(); std::cout << "ID: " << currentData.id << ", Value: " << currentData.value << std::endl; } ``` However, when I run a simple test with multiple threads, I get unexpected output like `ID: 0, Value: 0` or sometimes even garbage values. ```cpp int main() { std::thread t1(updateData, 1, 3.14); std::thread t2(printData); t1.join(); t2.join(); return 0; } ``` I assumed `std::atomic` would be able to handle my struct, but the data seems inconsistent. I tried switching to a plain `std::atomic<int>` for `id` and `std::atomic<double>` for `value`, but that made my code more complex and didn’t help with the overall design. Is there a specific reason why `std::atomic<Data>` doesn't work as expected with my struct? Should I be using a different approach to achieve thread safety for my custom data structure? Any advice would be greatly appreciated! I'm working with C++ in a Docker container on Linux. Any suggestions would be helpful. What's the correct way to implement this?