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c#javamultithreadingmemory-optimization
William
William

Reputation: 1895

What are the differences between the volatile in c# and java?

In some .net documentation I have read this is how the compiler handles volatile:

These fences apply at both complier and architecture level.

Of course the main difference in VC++ is that the fence is only applied at complier level.

So my question is, what are the memory reordering prevention semantics of volatile in Java?

Conversion:

Fence = Barrier Barrier = Fence

References:

Joe Duffy (Concurrent Programming on Windows)

Upvotes: 1

Views: 250

Answers (1)

Peter Lawrey
Peter Lawrey

Reputation: 533660

In Java, the javac compiler does next to nothing with volatile. It doesn't re-order statements and does almost no optimisation.

The JIT on the other hand can do quite a bit of optimisation and re-ordering.

The important features of volatile are;

  • read/write access cannot be optimise away
  • any write which occurs before a volatile write has to occur before the write.
  • any read which occurs after a volatile read, must occur after the read.

Upvotes: 1

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