C# Threading: a race condition example

Question

I am reading http://www.mono-project.com/ThreadsBeginnersGuide.

The first example looks like this:

public class FirstUnsyncThreads {
    private int          


        

Answer 1

When I run this (on a dualcore), my output is

First runner incrementing i from 0 to 1
Second runner incrementing i from 1 to 2
First runner incrementing i from 2 to 3
Second runner incrementing i from 3 to 4
First runner incrementing i from 4 to 5
Second runner incrementing i from 5 to 6
First runner incrementing i from 6 to 7
Second runner incrementing i from 7 to 8
First runner incrementing i from 8 to 9
Second runner incrementing i from 9 to 10

As I would have expected. You are running two loops, both executing Sleep(100). That is very ill suited to demonstrate a race-condition.

The code does have a race condition (as VoteyDisciple describes) but it is very unlikely to surface.

I can't explain the lack of order in your output (is it a real output?), but the Console class will synchronize output calls.

If you leave out the Sleep() calls and run the loops 1000 times (instead of 10) you might see two runners both incrementing from 554 to 555 or something.