std::vector invalidating iterators after insertion in a multi-threaded environment with C++17
I've tried everything I can think of but I've searched everywhere and can't find a clear answer. I can't seem to get I'm reviewing some code and This might be a silly question, but Quick question that's been bugging me - I'm experiencing unexpected behavior with `std::vector` in a multi-threaded C++17 application. I have a worker thread that inserts elements into a shared `std::vector`, and another thread that iterates over this vector. I expected the iterators to remain valid across insertions, but I noticed that I'm getting an `std::out_of_range` exception when the iterator is accessed after an insertion is made. Here's a simplified version of my code: ```cpp #include <iostream> #include <vector> #include <thread> #include <mutex> #include <chrono> std::vector<int> sharedVector; std::mutex vecMutex; void insertElements() { for (int i = 0; i < 10; ++i) { std::this_thread::sleep_for(std::chrono::milliseconds(100)); std::lock_guard<std::mutex> lock(vecMutex); sharedVector.push_back(i); std::cout << "Inserted: " << i << '\n'; } } void iterateElements() { while (true) { std::lock_guard<std::mutex> lock(vecMutex); for (auto it = sharedVector.begin(); it != sharedVector.end(); ++it) { std::cout << "Element: " << *it << '\n'; } std::this_thread::sleep_for(std::chrono::milliseconds(200)); } } int main() { std::thread inserter(insertElements); std::thread iterator(iterateElements); inserter.join(); iterator.join(); return 0; } ``` I've tried wrapping vector accesses in a mutex to protect against concurrent modifications, but I'm not sure if this is the correct approach. The exception seems to occur sporadically, especially when the insertions are happening frequently. Could it be that the iterator is invalidated due to the vector resizing? What would be the best way to handle this situation, and how can I ensure safe access to the vector from multiple threads without running into iterator invalidation issues? My development environment is Windows. Is there a better approach? I'm coming from a different tech stack and learning C++. This issue appeared after updating to C++ latest. My development environment is CentOS. Thanks in advance! My development environment is Ubuntu 22.04. I'm open to any suggestions.