[jcifs] SmbFile.listFiles() on own server takes a long time

[Michael B. Allen]

On Fri, 27 Sep 2002 11:49:56 +1000
"Kid Kalanon" <kid_kalanon at hotmail.com> wrote:

> Hi,
> 
> I'm experiencing a problem when trying to recursively list SmbFiles from 
> root (smb://).  I've found that it takes a long time when trying to list 
> shares from the local server.
> 
> Here's a bit of code to demonstrate this:
> ----------------------------------------------------
> 
> public class ListAll
> {
>   public static void main(String[] argv) throws Exception
>   {
>     SmbFile workgroup = new SmbFile("smb://workgroup");
>     SmbFile[] servers = workgroup.listFiles();
>     for (int i = 0; i < servers.length; i++) {
>       long startTime = System.currentTimeMillis();
>       try {
>         servers[i].listFiles();
>       }
>       catch (Exception ex) { }
>       System.out.println(servers[i] + " listFiles() took " +
>             (System.currentTimeMillis() - startTime) + " milliseconds");
>     }
>   }
> }
> 
> ----------------------------------------------------
> 
> the output looks like (the actual names have been removed to protect the 
> innocent):
> 
> smb://host1 listFiles() took 0 milliseconds

Wow, that's pretty fast. Urr, a little too fast actually.

> smb://host2 listFiles() took 47 milliseconds
> smb://host3 listFiles() took 0 milliseconds
> smb://host4 listFiles() took 6000 milliseconds

This is a name service lookup timeout. If you ex.printStackTrace()
you'll see that it's failing to lookup host4.

> smb://host5 listFiles() took 0 milliseconds
> smb://host6 listFiles() took 15 milliseconds
> 
> I am on a LAN with usually 5 to 6 computers running either Windows 2000 or 
> Windows NT and all on the same workgroup.  There are no Linux or Unix boxes 
> on the LAN.  As you can see, host4 is the culprit and that's the computer I 
> just run the above code on.

This sounds related to the WINs resolution problem just discussed. In
this case however I think you should be able to broadcast a name service
lookup to yourself. Weird. Can you send me a -Dlog=ALL trace of that?

> 
> I was wondering if anyone is experiencing a similar problem and more 
> importantly, does anyone know how to fix it?
> 
> 
> 
> That's the gist of the problem, here's a bit more detail if you're keen to 
> read on....
> 
> I've traced the problem down to NbtAddress class in method doNameQuery, 
> here's a stack trace (I'm using jcifs_0.7.0b3):
> 
> jcifs.netbios.NbtAddress.doNameQuery(NbtAddress.java:303)
> jcifs.netbios.NbtAddress.getByName(NbtAddress.java:431)
> jcifs.UniAddress.getByName(UniAddress.java:260)
> jcifs.UniAddress.getByName(UniAddress.java:186)
> jcifs.smb.SmbFile.getAddress(SmbFile.java:723)
> jcifs.smb.SmbFile.setTree(SmbFile.java:493)
> jcifs.smb.SmbFile.sendTransaction(SmbFile.java:503)
> jcifs.smb.SmbFile.listFiles(SmbFile.java:1233)
> jcifs.smb.SmbFile.listFiles(SmbFile.java:1152)
> com.arbiter.util.smb.ListAllServers.main(ListAllServers.java:110)
> 
> This function fails to find the NbtAdress (wrapper for ip address?) if the 
> name is is the local computer's name.
> 
> I suspect this behaviour is platform dependent and network dependent.  We're 
> not running any kind of "Name Server" or have configured anything special on 
> the Windows boxes when we connected them together (eg. didn't modify the 
> lmhosts.sam or hosts files) and this network is not expected to be 
> accessible from the outside world.  The Windows File Explorer can browse 
> networks fine and doesn't exhibit this problem ;)
> 
> The workaround for this problem I used was to add the following code to 
> UniAddress.getByName before any lookup is done:
> 
> if (hostname.equalsIgnoreCase(
>       InetAddress.getLocalHost().getHostName()) ) {
>   return new UniAddress( InetAddress.getLocalHost() );
> }
> 
> This, most likely is not the right way.  I don't understand the inner 
> workings that well.  Can anyone suggest something better?
> 
> 
> Kid.
> 
> 
> 
> 
> 
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