One thread read and one thread write, is std::deque safe?

Question

Read thread calls at(i) function and write thread calls push_back() function, I get the error "out of range", Why?

I think that the variable of `size()` remains in each core's register? by using `volatile`, can we solve the problem for the certain situation that "one read one write"? — egraldlo, Nov 15 '16 at 11:05
write a self defined queue, define function `size()` by using `volatile` variable count. — egraldlo, Nov 15 '16 at 11:12
You cannot use `volatile` for synchronization. Period. Writing a concurrent queue is not *that* easy. — Baum mit Augen, Nov 15 '16 at 11:14

score 3 · Answer 1 · answered Nov 15 '16 at 10:56

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Calling any non-const member function on any standard library object is not thread-safe (unless a particular non-const function is documented otherwise). You need to synchronise access to the object to prevent data races and thus Undefined Behaviour.

answered Nov 15 '16 at 10:56

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Using the "at" function for a deque is also pretty inefficient. – Sven Nilsson Nov 15 '16 at 10:57

One thread read and one thread write, is std::deque safe?

1 Answers1