How to multithread queue processing

C++ containers are supposed to be thread-safe by default. I must be using `queue` to multithread incorrectly because for this code: ``` #include <thread> using std::thread; #include <iostream> using std::cout; using std::endl; #include <queue> using std::queue; #include <string> using std::string; using std::to_string; #include <functional> using std::ref; void fillWorkQueue(queue<string>& itemQueue) { int size = 40000; for(int i = 0; i < size; i++) itemQueue.push(to_string(i)); } void doWork(queue<string>& itemQueue) { while(!itemQueue.empty()) { itemQueue.pop(); } } void singleThreaded() { queue<string> itemQueue; fillWorkQueue(itemQueue); doWork(itemQueue); cout << "done\n"; } void multiThreaded() { queue<string> itemQueue; fillWorkQueue(itemQueue); thread t1(doWork, ref(itemQueue)); thread t2(doWork, ref(itemQueue)); t1.join(); t2.join(); cout << "done\n"; } int main() { cout << endl; // Single Threaded cout << "singleThreaded\n"; singleThreaded(); cout << endl; // Multi Threaded cout << "multiThreaded\n"; multiThreaded(); cout << endl; } ``` I'm getting: ``` singleThreaded done multiThreaded main(32429,0x10e530000) malloc: *** error for object 0x7fe4e3883e00: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug make: *** [run] Abort trap: 6 ``` What am I doing wrong here? EDIT Apparently I misread the link above. Is there a thread-safe queue implementation available that does what I am trying to do? I know this is a common thread organization strategy.