Is a volatile int in Java thread-safe?

java multithreading thread-safety volatile
shawn picture shawn · Oct 18, 2011 · Viewed 33.7k times · Source

Is a volatile int in Java thread-safe? That is, can it be safely read from and written to without locking?

Answer

Jon Skeet picture Jon Skeet · Oct 18, 2011

Yes, you can read from it and write to it safely - but you can't do anything compound such as incrementing it safely, as that's a read/modify/write cycle. There's also the matter of how it interacts with access to other variables.

The precise nature of volatile is frankly confusing (see the memory model section of the JLS for more details) - I would personally generally use AtomicInteger instead, as a simpler way of making sure I get it right.

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