Does a correctly synchronized program still allow data race?(Part I)

Question

There are two conclusions from JLS:

• C1: If a program is free of data races, then all executions of the program will appear to be sequentially consistent:

Answer 1

Race conditions mean to let your program's output depend on who gets at a specific point first. For instance, if you have 2 threads: T1 and T2, if your programs output is X if T1 gets to point P in the program first and the program's output is Y if T2 gets to point P first, then you have a race condition.

In pseudocode:

 Global variable i initialized to 6;
 Thread 1: 
       aquire(lock l)
             increment global variable i, i.e. i++;


 Thread 2: 
       aquire(lock l)
             double the value of global var i, i.e.: i*=2;

If T1 aquires the lock l firts and T2 second the value of i will be 14 If T2 aquires the lock l firts and T1 second the value of i will be 13