[jcifs] Peformance questions

Michael B Allen ioplex at gmail.com
Sun Mar 3 18:58:45 MST 2013

On Feb 28, 2013 12:59 AM, "Philip Warner" <pjw at rhyme.com.au> wrote:
> On 28/02/2013 3:45 PM, Michael B Allen wrote:
> > JCIFS should absolutely not be querying DFS during writes and I would
be surprised if it actually is. That is something that would
> > require a proper capture to verify.
> You are probably right about this, but based on 1.3.14 sources:
>     SmbFileOutputStream.writeDirect(...) calls SmbFile.send(...)
>     SmbFile.send(...) calls resolveDfs(...)
>     resolveDfs(...) calls Dfs.resolve(...)

Hi Philip,

The those DFS methods should just return immediately after being called
once. They cache results.

> Dfs.resolve(...) looks like it does OS-level network stuff unless DFS is
disabled, or unless it has succeeded in a call to
> Dfs.resolve(...) recently.
> My suspicion is that because DFS is enabled, and because DFS is not
present, it is retrying for every block it sends. Hence the 400%
> slowdown when DFS is enabled.

I doubt very much that is happening.  But if you can produce a capture that
shows a problem I'll fix it (eventually).

> Or it could just the the OS-level calls are really slow.

Jcifs does not call any OS specific functions. It is 100% java.


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