Safe parallel read-only access to a STL container

Question

I want access a STL based container read-only from parallel running threads. Without using any user implemented locking. The base of the follow

Answer 1

A data-race, from the C++11 specification in sections 1.10/4 and 1.10/21, requires at least two threads with non-atomic access to the same set of memory locations, the two threads are not synchronized with regards to accessing the set of memory locations, and at least one thread writes to or modifies an element in the set of memory locations. So in your case, if the threads are only reading, you are fine ... by definition since none of the threads write to the same set of memory locations, there are no data-races even though there is no explicit synchronization mechanism between the threads.