[Zope-dev] Slow FTP Downloads - Zope 2.6.4, 2.7

[Edward Pollard]

Some of you might recognize this thread from the zope at zope.org mailing 
list. With great reluctance smothered by desperation I thought it might 
be fruitful to disseminate it on this list as well.

We have been using Zope 2.6.0 for some time. When we decided an upgrade 
was in order (to get away from ZODB killing maintenance tools), we 
moved to Zope 2.6.2, as that was what was available at the time. At the 
tail end of that upgrade, we discovered some crippling FTP bugs which 
seem to have been acknowledged and fixed in later revisions.

Attempts to move to Zope 2.6.4 and 2.7 have been stymied, however, 
since any servers we have set up with these versions of Zope refuse to 
allow users to download via FTP faster than 10k/second. During these 
downloads, the CPU shoots straight to 100%. While we can have 10 
different connections active, they all go at 10k/sec and the CPU is 
always at 100% regardless of how many connections we have. This is 
across a variety of FTP clients, so we don't think that is related to 
the issue.

Experiments with the Profiler have been fruitless, and lack of 
experience with strace has blocked any progression at locating this 
problem with that, aside from noting an tremendous amount of failed 
open and stat64 calls - but since these are also in 2.6.0 I am not 
inclined to believe them significant to this problem.

The server is a Dell Poweredge 1750 single processor 2.4GHz P4 Xeon 
with hyper-threading. RedHat 9 is running on the hardware mirrored 
internal HD, Zope on a NFS mounted (via TCP) volume. Moving Zope to the 
local disk and disabling hyper-threading has had no impact on this 
problem.

So far, all I've been able to determine is that nobody else is having 
this problem. My mom always said I was special.

Anyone with thoughts not previously shared on the other list? My only 
option at this point seems to be to go back to 2.6.0 while keeping 
later revisions on the ZODB tools. An inability to eventually rectify 
this problem would be pretty hard blow against using Zope at our 
institution, however, so I'm trying to avoid seriously contemplating 
that decision since I've grown so fond of Zope.

---
Edward J. Pollard, B.Sc
Webmaster, University of Lethbridge