The implication (in fact no, it's explicitly stated) is that this fsync() behaviour on OSX will be a surprise for developers working on cross platform code or coming from other OS's and will catch them out.
However if in fact it's quite common for other OS's to exhibit the same or similar behaviour (BSD for example does this too, which makes sense as OSX has a lot of BSD lineage), that argument of least surprise falls a bit flat.
That's not to say this is good behaviour, I think Linux does this right, the real issue is the appalling performance for flushing writes.
The implication (in fact no, it's explicitly stated) is that this fsync() behaviour on OSX will be a surprise for developers working on cross platform code or coming from other OS's and will catch them out.
However if in fact it's quite common for other OS's to exhibit the same or similar behaviour (BSD for example does this too, which makes sense as OSX has a lot of BSD lineage), that argument of least surprise falls a bit flat.
That's not to say this is good behaviour, I think Linux does this right, the real issue is the appalling performance for flushing writes.