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https://issues.apache.org/jira/browse/LUCENE-5738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14019675#comment-14019675
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Michael McCandless commented on LUCENE-5738:
--------------------------------------------
+1, patch looks good
I wouldn't use the world elegant: this is an annoying JDK trap that we have to
work around!
You changed the test to also sometimes try to acquire the lock (in the same
process) when it already has the lock, and assert that 2nd acquire failed.
With the bug, this would release the first lock the process had acquired,
allowing the 2nd process to illegally obtain the lock, and then the server
fails.
Can you rename LOCK_MARKERS to LOCK_HELD (and clearMarkedLock to clearHeldLock)
to make it clear that's the purpose of the map? Also the indent of
clearMarkedLock is off.
> NativeLock is release if Lock is closed after obtain failed
> -----------------------------------------------------------
>
> Key: LUCENE-5738
> URL: https://issues.apache.org/jira/browse/LUCENE-5738
> Project: Lucene - Core
> Issue Type: Bug
> Affects Versions: 4.8.1
> Reporter: Simon Willnauer
> Assignee: Simon Willnauer
> Fix For: 4.9, 5.0
>
> Attachments: LUCENE-5738.patch
>
>
> if you obtain the NativeFSLock and try to obtain it again in the same JVM and
> close if if it fails another process will be able to obtain it. This is
> pretty trappy though. If you execute the main class twice the problem becomes
> pretty obvious.
> {noformat}
> import org.apache.lucene.store.Lock;
> import org.apache.lucene.store.NativeFSLockFactory;
> import java.io.File;
> import java.io.IOException;
> public class TestLock {
> public static void main(String[] foo) throws IOException,
> InterruptedException {
> NativeFSLockFactory lockFactory = new NativeFSLockFactory(new
> File("/tmp"));
> Lock lock = lockFactory.makeLock("LOCK");
> if (lock.obtain()) {
> System.out.println("OBTAINED");
> } else {
> lock.close();
> System.out.println("FAILED");
> }
> // try it again and close it if it fails
> lock = lockFactory.makeLock("LOCK"); // <<<<==== this is a new lock
> if (lock.obtain()) {
> System.out.println("OBTAINED AGAIN");
> } else {
> lock.close(); // <<<<==== this releases the lock we obtained
> System.out.println("FAILED on Second");
> }
> Thread.sleep(Integer.MAX_VALUE);
> }
> }
> {noformat}
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