Re: [jgit-dev] nio exception

[Shawn Pearce <spearce@xxxxxxxxxxx>]

On Tue, Mar 6, 2012 at 05:16, Markus Duft <markus.duft@xxxxxxxxxx> wrote:
> i keep getting things like this in various places all over on linux:
>
> Caused by: java.nio.channels.ClosedByInterruptException
>        at java.nio.channels.spi.AbstractInterruptibleChannel.end(AbstractInterruptibleChannel.java:201)
>        at sun.nio.ch.FileChannelImpl.size(FileChannelImpl.java:335)
>        at org.eclipse.jgit.util.IO.readFully(IO.java:140)
>        at org.eclipse.jgit.util.IO.readFully(IO.java:78)
>        at org.eclipse.jgit.storage.file.ReflogReader.getReverseEntries(ReflogReader.java:130)
>        at org.eclipse.jgit.storage.file.ReflogReader.getReverseEntries(ReflogReader.java:88)
>        at org.eclipse.jgit.api.ReflogCommand.call(ReflogCommand.java:92)
>        ... 47 more

NIO shouldn't be used in a multi-threaded program that might use
Thread.interrupt():

  http://blog.spearce.org/2010/05/dont-assume-you-know-whats-best.html

A long time ago I switched the pack file access code away from NIO
because of this problem. I didn't realize we were still using NIO for
the ReflogReader. Ick.

> any thoughts? i happened to get this for reads of the .git/config file previously sporadically since 1.1,

I didn't realize the config file reader used NIO either. I thought
that was a simple FileInputStream.

> but now it also happened for the stash feature (which is new for me - i fetched from the repos today).

Ick. JGit as a library really cannot rely on using NIO, or needs to be
more careful where it is used. If the embedding application sends an
interrupt to a thread that JGit has doing file IO using NIO, JGit
needs to be prepared for the file being closed as the interrupt is
delivered. One can argue that at least delivering the interrupt
instead of doing the requested IO operation is the right behavior, as
its likely the user has requested the operation to cancel (IIRC
Eclipse sends an interrupt on the cancel/stop button in a progress
bar) so doing more IO is maybe not a good idea. But closing the file
handle automatically like NIO does is really evil.