std::unique_ptr with custom deleter causing memory leaks in multithreaded environment
I'm working with an scenario where using `std::unique_ptr` with a custom deleter in a multithreaded environment seems to be causing memory leaks. I'm using C++17 along with the standard threading library. My custom deleter is supposed to delete an instance of a class that manages a resource, but it appears that sometimes it's not being called, leading to leaked memory. Here’s a simplified version of what I’ve implemented: ```cpp #include <iostream> #include <memory> #include <thread> #include <vector> class Resource { public: Resource() { std::cout << "Resource acquired." << std::endl; } ~Resource() { std::cout << "Resource released." << std::endl; } }; void threadFunction(std::unique_ptr<Resource, std::function<void(Resource*)>> uptr) { // Simulating some work with the resource std::this_thread::sleep_for(std::chrono::milliseconds(100)); } int main() { std::vector<std::thread> threads; for (int i = 0; i < 5; ++i) { auto deleter = [](Resource* r) { std::cout << "Custom deleter called." << std::endl; delete r; }; auto uptr = std::unique_ptr<Resource, std::function<void(Resource*)>>(new Resource(), deleter); threads.emplace_back(threadFunction, std::move(uptr)); } for (auto& t : threads) t.join(); return 0; } ``` When I run this code, the messages from the `Resource` destructor and my custom deleter do not always appear for each `Resource` instance, suggesting that they are not being properly managed. I suspect the scenario might be related to how `std::unique_ptr` is being passed to the threads or perhaps the ownership semantics. I've tried debugging with `valgrind`, but it only shows that there are leaked allocations without much detail on where the scenario originates. Am I missing something in the way I manage the ownership of the `std::unique_ptr` in this multithreaded setup? Any insights would be greatly appreciated!