Using FileChannel to fsync a directory with NIO.2

Question

I just discovered that with NIO.2, at least under Linux, I can open a FileChannel on a directory, and calling force(true) calls fsync() on the underlying file descriptor. Without getting into whether this should be necessary, it's nice to finally have this functionality available in pure Java.

I haven't been able to find anywhere that this behaviour is documented, though. Can I count on this working on all Unix platforms, in future versions of Java, and in non-Oracle JVMs?

http://stackoverflow.com/questions/5650327/are-filechannel-force-and-filedescriptor-sync-both-needed — Perception, Oct 08 '11 at 02:21
That's about files; only Java 7 seems to allow `fsync` on directories, and I'd like to know if this is on purpose. — Carey, Oct 08 '11 at 04:54

score 3 · Accepted Answer · answered Jun 09 '15 at 20:31

3

See the following thread: http://mail.openjdk.java.net/pipermail/nio-dev/2015-May/003140.html

It was not technically supported, but looks like support will be retained as many applications rely on it.

answered Jun 09 '15 at 20:31

Mark

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score -1 · Answer 2 · answered Oct 08 '11 at 09:26

-1

You can count on whatever the documentation says, and on nothing else.

answered Oct 08 '11 at 09:26

user207421

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Unlike `FileInputStream`, the documentation for `FileChannel.open()` doesn’t say that it only works on regular files, which I guess will have to do. – Carey Oct 13 '11 at 02:58

Using FileChannel to fsync a directory with NIO.2

2 Answers2

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