Explain Race condition in details with an example ?

Please refer our last post to understand the race condition explanation, 

 

Consider that there are two threads of execution, both enter below critical region, and the initial value of i is 3. The desire

Thread 1                                                                Thread 2
get i (3)                                                                       —
increment i (3 ­> 4)                                                    —
write back i (4)                                                           —
—                                                                           get i (4)
—                                                                           increment i (4 ­> 5)
­­­                                                                           write back i (5)

As expected, 3 incremented twice is 5. A possible outcome, however, is the following:

Thread 1                                                                 Thread 2
get i (3)                                                              get i (3)
increment i (3 ­> 4)                                            —
—                                                                       increment i (3 ­> 4)
write back i (4)                                                   —
—                                                                       write back i (4)
 
If both threads of execution read the initial value of i before it is incremented, both
threads increment and save the same value. As a result, the variable i contains the value
3 when, in fact, it should now contain 4. This is one of the simplest examples of a
critical region.