Multiple ChoiceIntermediate 45s
std::call_once Guarantees
What does std::call_once guarantee when multiple threads invoke it with the same once_flag?
Options
- 1The function runs at most once, and all callers synchronize with the completed call
- 2The function runs once per calling thread, so each caller gets its own invocation
- 3The function may run twice concurrently and the two results are merged afterwards
- 4It deadlocks whenever two or more threads call it with the same flag concurrently
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