How do I merge two containers efficiently with std::map in multithreaded code?

Merging two std::map containers efficiently in a multithreaded environment requires careful handling to avoid data races and ensure thread safety. Here’s a concise guide on how to accomplish this using mutexes to synchronize access to the maps.

To merge two maps, you can iterate over the second map and insert elements into the first map. Use a mutex to lock the maps during this operation to maintain thread safety. Below is an example demonstrating how to do this.

#include #include #include #include std::map map1; std::map map2; std::mutex mtx; void mergeMaps() { std::lock_guard<:mutex> lock(mtx); for (const auto& pair : map2) { map1[pair.first] = pair.second; } } int main() { // Initialize map1 and map2 map1[1] = "A"; map1[2] = "B"; map2[2] = "Changed B"; // This will replace the B in map1 map2[3] = "C"; std::thread t1(mergeMaps); std::thread t2(mergeMaps); t1.join(); t2.join(); // Print merged map for (const auto& pair : map1) { std::cout << pair.first << ": " << pair.second << std::endl; } return 0; }

C++ std::map multithreading merge maps thread safety mutex

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