We are doing every day a long bogofilter -s/-n (about two consecutive hours a day)
when this process is finishing (when write locks are acquired on the database) all
bogofilter -p operations are put on hold until the locks are released. As we use
bogofilter -p in mail processing, exim just kills this waiting process (timed out).
When looking at datastore_db.c I noticed that locks are acquired with fcntl on
all the database, maybe it could be better to use Berkeley db own's locking (?)