When multiple threads are updating ***isSame*** variable

isSame &= isSameTreeMultiThreaded(p.left, q.left, numThreads/2);
SIMILAR TO
isSame = isSame & isSameTreeMultiThreaded(p.left, q.left, numThreads/2);

1. It reads isSame which is thread safe gives latest value due to primitive
2. & operator with isSame variable ( one more, by the time it evaluates through recursive function, isSame variable could be outdated )
3. Updating isSame variable which is thread safe due to primitive

But, All the above 3 steps together is not atomic.

Consider the scenario:

isSame is true by default,

1. Thread-1 reads as true
2. Thread-2 reads as true
3. Thread-1 receives false from recursive function and updates it with *false