Are 64 bit assignments in Java atomic on a 32 bit machine?

Question

If I have code like this -

long x;
x  = 0xFFFFFFFFL;

If i run this code on a 32 bit machine is it guaranteed to be atomic or is it po

Answer 1

No they are not. A 64 bit store is treated as two separate 32 bit stores. So in a concurrent environment that variable can have the high 32 of one write and the low 32 of another write, obviously not thread safe.