deadlock using sequences?

(Accidently posted to pgadmin-support.)

Hi,

I get occasional deadlocks when using sequences from
multiple clients.

Here's the table DDL:

create sequence ids;
create table foo( id integer default nextval('ids'),
parent integer, type char(4), name text, value text )
without oids;
create index xml_id on xml(id);

I'm inserting 1000s of tuples from 4-5 different
clients (all use JDBC but are single threaded).
About once every 1000 tuples I get

ERROR:  deadlock detected

I can't use OIDS because I have to guarantee
monotonically increasing ids.

Any ideas? Shouldn't sequences be implemented deadlock
free?

Thanks.

-- Lars