Thread safety of std::mutex

Question

Can I lock std::mutex in one thread and unlock it in other thread? This is theoretical question without any specific engineering context. I am just curious.

No. See also http://www.geeksforgeeks.org/mutex-vs-semaphore/ — yohjp, Dec 03 '14 at 07:46

score 7 · Accepted Answer · edited Jun 20 '20 at 09:12

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C++ standard, [thread.mutex.requirements.mutex]/21 and 22:

The expression m.unlock() shall be well-formed and have the following semantics:

Requires: The calling thread shall own the mutex.

A violation of requirements in a Requires clause induces undefined behavior.

edited Jun 20 '20 at 09:12

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answered Dec 02 '14 at 19:37

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score 6 · Answer 2 · answered Dec 02 '14 at 19:36

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cppreference reads:

The mutex must be locked by the current thread of execution, otherwise, the behavior is undefined.

answered Dec 02 '14 at 19:36

Thread safety of std::mutex

2 Answers2