[OpenAFS-devel] Performance of Thunderbird on windows with mail folders stored in AFS

[Douglas E. Engert]

I have been using Thunderbird on W7 with my mail folder and profile
stored in AFS. Performance was not great but acceptable until recently.

The main problem appears to be Thunderbird's handing of Copy, Move
and Delete (Copy to Trash) operations as it buffers the input but
writes one output line at a time. Base 64 encode attachments tend
to have a line length of 74 or 78 bytes, and thus a 3.8MB file
may require 50,000 writes. And this can take more then 60 seconds
and the TB client shows "(Not Responding)" on the title bar.

I have submitted a suggested 2 line patch for Thunderbird 13.0.1 to
buffer the writes in an 8K buffer, and cut the delete time from
more then 60 seconds to less then 2 seconds.

  https://bugzilla.mozilla.org/show_bug.cgi?id=769346

Mozilla has "fixed" many performance bugs like this, including
using buffering, but these problems keep coming back, and are
back in TB 12.0, 13.0 and 13.0.1.

While trying to figure out why performance was getting worse,
I kept upgrading TB and OpenAFS clients on Windows 7 and
was running TB 12.0 and OpenAFS 1.7.15 with performance
getting worse rather then better.

The OpenAFS Change log says:

     Since 1.7.1100 (1.7.11)
     * Treat all cached writes as write-through

This appears to have complicated the matter, and while trying to
figure what was going on, I backed off to 1.7.1000, prior to that
change. I will be on vacation next week, waiting to hear if anyone
at Mozilla reads the bug report, or if there is some changes to
OpenAFS that could improve handing of small writes.

I expect to work on the patch some more in a few weeks, and go back
to OpenAFS 1.7.1500 as it appears to fix some other problems that
the 1.7.1000 has.

-- 

  Douglas E. Engert  <DEEngert@anl.gov>
  Argonne National Laboratory
  9700 South Cass Avenue
  Argonne, Illinois  60439
  (630) 252-5444