What about race condition in multithreaded reading?
Reading memory at hardware level is done sequentially - you don't need to worry about concurrency at this level. Two threads issue read instructions and all the necessary stuff - setting addresses on the address bus and actual reads are implemented by the memory access hardware in such way that reads will always work right.
In fact the same is true for read/write scenarios except that when read and write requests are interleaved you will get different results depending on timing and this is why you need synchronization.
As long as there's nothing changing the data, it's perfectly safe to be reading it from several threads. Even if two CPUs (or cores) race to access the memory for reading at the exact same clock cycle, their accesses will be serialized by the memory controller and they won't interfere with each other. This feature is essential for HW working correctly.
There is not a simple answer to this question. Different API's (and different environments) will have different levels of multhreaded-awareness and multithreaded safety.