[int_19h]

> Contrast that with Windows programming or, especially, Java, where the expectation is that objects are shareable and guarantee thread-safety internally.

That's not an expectation on either. For example, the single most common phrase you can see on MSDN in class docs is: "Public static members of this type are thread safe. Any instance members are not guaranteed to be thread safe."

There was a period when it was different for some things. In particular, both Java and .NET had thread-safe standard collection classes initially - e.g. Vector in Java, ArrayList in .NET. This has proven to be a bad trade-off in both cases - it's a massive perf hit for something that's not even all that useful even to threaded code, because in practice you often need to perform multiple operations on the collection atomically, and then you still need your own lock.

So they have since been obsoleted by new collections that do not attempt to do any thread synchronization; the old collections remain for backwards compatibility purposes. Modern idiomatic Java or C# code doesn't do any kind of synchronization or locking to protect the caller, unless that is specifically the purpose of this class or function to provide such things.

So I wouldn't say there's significant cultural differences between Windows, Unix and Java in that regard.