c# - Volatile Violates its main job?

Question

According to MSDN:

The volatile keyword indicates that a field might be modified by multiple threads that are executing at the same time. Fields that are declared volatile are not subject to compiler optimizations that assume access by a single thread. This ensures that the most up-to-date value is present in the field at all times.

Please notice the last sentence:

This ensures that the most up-to-date value is present in the field at all times.

However, there's a problem with this keyword.

I've read that it can change order of instructions:

First instruction       Second instruction         Can they be swapped?
Read                         Read                         No
Read                         Write                        No
Write                       Write                         No 
Write                       Read                          Yes! <----

This means John sets a value to a volatile field, and later Paul wants to read the field, Paul is getting the old value!

What is going here ? Isn't that it's main job ?

I know there are other solutions, but my question is about the volatile keyword.

Should I (as a programmer) need to prevent using this keyword - because of such weird behavior ?

Answer 1

Well you are right. It is more elaborated in Joseph Albahari threading book/article.

The MSDN documentation states that use of the volatile keyword ensures that the most up-to-date value is present in the field at all times. This is incorrect, since as we’ve seen, a write followed by a read can be reordered.

http://www.albahari.com/threading/part4.aspx#_The_volatile_keyword

Should I ( as a programmer ) need to prevent using this keyword-because of such weird behavior?

It should be used only after knowing this weired behavior. It should not be used as a Magic keyword to retrieve latest values all the time in multithreaded environment.

IMO, usage of volatile keyword should be avoided as probable bugs are hard to find out.