Is accessing different elements of an array thread-safe?

[parmi93]

char my_array[10];

Let's say threadA changes the value of my_array[0] and threadB changes the value of my_array[1] , is this thread safe?

My instinct tells me that it is not thread-safe, because since arrays cannot have padding bytes between elements, and usually CPU access (read/write) multiple bytes at a time, that means changing the value of my_array[0] would result in writing adjacent array elements which may have changed in the meantime.

More specifically, is this guaranteed to be thread-safe with single core MCUs without cache?

And if this is thread-safe, is this guaranteed by the CPU or by ThreadX?

[amgross]

Hi @parmi93 ,
From what I saw in threadx code, in case of interrupt context may switch immediately, hence there is no protection in threadx level.

Hence the answers you got in freertos forum are probably good also for here (is-accessing-different-elements-of-an-array-thread-safe).