False sharing is something that happens when our program has two unrelated data elements that are mapped to the same cache line/location. That can be because of bad luck (hash collision kind of problem), but it often takes place because the data elements are stored consecutively.

char a[10];
char b[10];

These two chars are likely allocated contiguous in memory, so invalidating one array invalides the other array. We can just increase the array size to ensure that they are not contiguous.