What is a race condition?

Question

When writing multithreaded applications, one of the most common problems experienced is race conditions.

My questions to the community are:

What is the rac

Answer 1

A race condition is a kind of bug, that happens only with certain temporal conditions.

Example: Imagine you have two threads, A and B.

In Thread A:

if( object.a != 0 )
    object.avg = total / object.a

In Thread B:

object.a = 0

If thread A is preempted just after having check that object.a is not null, B will do a = 0, and when thread A will gain the processor, it will do a "divide by zero".

This bug only happen when thread A is preempted just after the if statement, it's very rare, but it can happen.