With multithreading, you have to be careful to not create race conditions. The default way to do this is the usage of mutexes at all critical sections. This is annoying, reduces performance and can lead to deadlocks. For some scenarios, it’s a possibility to instead use atomics or lock-free containers.<\/p>\n
… can be used to sync anything.<\/p>\n
\r\nstd::mutex mtx;\r\nint num = 0;\r\n\r\nvoid inc() {\r\n std::lock_guard<std::mutex> lock(mtx);\r\n num++;\r\n}\r\n\r\nint main() {\r\n std::thread t1(inc), t2(inc);\r\n return 0;\r\n}\r\n<\/pre>\n
\nAlternatives<\/h2>\nAtomics<\/h3>\n
… are used to sync primitive types.<\/p>\n
\r\nstd::atomic<int> num = 0;\r\n\r\nvoid inc() {\r\n num++;\r\n}\r\n\r\nint main() {\r\n std::thread t1(inc), t2(inc);\r\n return 0;\r\n}\r\n<\/pre>\nDepending on the use case, atomics are not necessarily more performant than locks.<\/p>\n
Lock-free containers<\/h3>\n
… don’t need to sync at all.<\/p>\n