Program doesn't exit normally after execution

[testphreak]

Hi @DavidASeibert, thank you for the excellent NFSv3 Java client. I just started using it to test read/write access to an NFS share. I wrote a short program to test read access. Something odd I notice, is that the program doesn't exit normally. Can't figure out why and I have to exit the program manually. Any idea why this might be happening? I am using JDK 1.8.0_131 on Mac OS X (Sierra).

public class NFSClient {

    public static void main(String args[]) {
        try {

            Nfs3 nfs3 = new Nfs3("10.x.x.x", "/testdir/",
                    new CredentialUnix(0, 0, null), 3);

            Nfs3File nfs3File = new Nfs3File(nfs3, "/testsubdir/");

            if (nfs3File.canRead()) {
                System.out.println(nfs3File.listFiles());
            } else {
                System.out.println("No read permission");
            }

        } catch (IOException e) {
            System.out.println(e);
        }
    }
}

I am able to establish a connection and list the files in the program above, but can't figure out why it won't exit. Please let me know if you need more information.

Additional information: The NFS share is a AWS Storage File Gateway, which offers NFS mount for S3.

[testphreak]

The only way I have found so far to ensure the program exits normally, is by shutting down NetMgr:

finally {
   NetMgr.getInstance().shutdown();
}

This isn't ideal, but I'd like to know if there's a better way to shut down any running threads and exit gracefully. The tests don't have an example either, so I am not sure.

[DavidASeibert]

Thanks, @testphreak. I will investigate.

[brunchboy]

It sounds like the NetMgr creates one or more threads that should really be marked as daemon threads before starting them, as they are not supposed to prevent program termination.

[brunchboy]

To be specific, the problem is here: https://github.com/EMCECS/nfs-client-java/blob/master/src/main/java/com/emc/ecs/nfsclient/network/NetMgr.java#L67-L68

This code should be calling the version of newCachedThreadPool() which takes a ThreadFactory argument, and passing in a ThreadFactory that sets the created threads to be daemon threads, an example of which is shown in this answer: https://stackoverflow.com/questions/13883293/turning-an-executorservice-to-daemon-in-java

(Note that this needs to be done for both newCachedThreadPool() calls.)

[DavidASeibert]

I think that all necessary changes are in https://github.com/EMCECS/nfs-client-java/tree/feature-use-daemon-threads. Can you confirm, @testphreak ?

[DavidASeibert]

Fixed in master after PR merge.