Question

If each thread is guaranteed to only read/write to a specific subset of the array can multiple threads work on the same (static) array without resorting to critical sections, etc?

EDIT – This is for the specific case of arrays of non-reference-counted types and record/packed-records thereof.

If yes, any caveats?

My gut feeling is yes but my gut can sometimes be an unreliable source of information.

Answer 1

Suppose that:

1. You have a single instance of an array (static or dynamic), and
2. The elements of the array are pure value types (i.e. contain no references), and
3. Each thread operates on disjoint sub-arrays, and
4. Nothing else in the system writes to the array whilst the threads are operating on it.

With these conditions, which I believe are met by your data structure and threading pattern, then all algorithms are thread-safe.