Hi
You have several ways to do it:
1) Use NativeFSLockFactory, which obtains native locks that are released
automatically when the process dies, as well as after a successful
IndexWriter.close(). If your writer.close() is called just before the
process terminates, then this might be a good solution.
2) You can call writer.rollback() if close() (or any operation) failed, in
code similar to this:
boolean success = false;
try {
// do something with IndexWriter, e.g.:
writer.close();
success = true;
} finally {
if (!success) {
writer.rollback();
}
}
You should try to avoid calling unlock() as much as possible. It's a
dangerous method.
Shai
On Mon, Jun 4, 2012 at 4:59 PM, Geoff Cooney <cooney.ge...@gmail.com> wrote:
> Hi,
>
> Is there a safe way to forcefully close an IndexWriter that is unable to
> flush to disk? We're seeing occasional issues where an IndexWriter
> encounters an IOException on close and does not release the write lock.
> The IndexWriter documentation lists this as desired behavior so that
> clients can attempt to fix the cause of the problem(e.g. free up memory)
> and then re-commit. The recommendation from the javadoc is that if you
> can't(or don't want to) fix the issue, you can release the lock like this:
>
> try {
> writer.close();
> } finally {
> if (IndexWriter.isLocked(directory)) {
> IndexWriter.unlock(directory);
> }
> }
>
> However, this does not seem safe to me as it works off of a static
> method which gets the lock object and then another static method to
> release the lock. In the case where the writer closed normally, it's
> possible another IndexWriter has grabbed the lock before the finally
> code executes, which could result on an IndexWriter with a revoked
> lock continuing to do indexing work.
>
> Is there a safer way to release the IndexWriter lock that I'm missing.
> If not, would lucene be open to a patch to provide a safe mechanism
> for releasing the lock? I would be happy to contribute one if so. I
> can think of a couple viable approaches:
>
> 1) Provide an additional close API call that takes a forceClose
> argument. When forceClose=true, IndexWriter would release the lock
> even when an error occurs.
>
> 2) Provide a method to release the lock and document that once called
> the IndexWriter should be thrown out.
>
> 3) Make the write lock protected so that applications that want to
> can subclass IndexWriter and provide a mechanism to release the lock
>
> Cheers,
>
> Geoff
>
