Obtaining write lock when trying to write index error

Haloo.

I’ve noticed some weird behaviour while trying ferret with rails
without act_as_ferret plugin: when I start application under
lighttpd proxying requests to spawned fcgi processes, I see this:

: Error occured at :703 Error: exception 6 not handled: Could not
obtain write lock when trying to write index

The same time everything goes ok with webrick. Indexing part for the
model is as simple as

def index
index = get_index
index << to_ferret_document #
[RAILS_ROOT]/lib/searchable_model.rb:5:in `<<’
index.flush
index.optimize
index.close
end

def get_index
Ferret::Index::Index.new(:path =>
APP::CONFIG[:store_indexes_directory],
:analyzer =>
FerretConfig::CONTENT_ANALYZER,
:create_if_missing => true)
end

I supposed that working with index this way would be okay (according
to http://ferret.davebalmain.com/trac/wiki/HowTos), but it looks like
i’v missed some kind of top-secret ferret config parameter maybe or
smth., so couldnt you share that trick with me ? (Iam sure every one
knows that). Thanks.

moe.