We need to lock a .NET Int32 when reading it in a multithreaded code?

Question

I was reading the following article: http://msdn.microsoft.com/en-us/magazine/cc817398.aspx \"Solving 11 Likely Problems In Your Multithreaded Code\" by Joe Duffy

An

Answer 1

It depends exactly how you're going to use the 32-bit number.

If you wanted to perform an operation like:

i++;

That implicitly breaks down into

1. reading the value of i
2. adding one
3. storing i

If another thread modifies i after 1, but before 3, then you have a problem where i was 7, you add one to it, and now it's 492.

But if you're simply reading i, or performing a single operation, like:

i = 8;

then you don't need to lock i.

Now, your question says, "...need to lock a .NET Int32 when reading it..." but your example involves reading and then writing to an Int32.

So, it depends on what you're doing.