I'm not sure exactly what you're looking for, but Berkeley DB is embedded in your application on a single host, while HyperDex is distributed. It sounds like that's exactly what you want.
What do you use exclusive locks for?
What do you use exclusive locks for?
For example, the GUI engine may eventually start cleaning its old cache, and the exclusive lock prevents other GUI processes (which are mod_perl or fcgi processes) to do the same.
another example is when the database is big enough, and when multiple collector processes start at the same time, I use the exclusive lock to let them initialize and slurp the data sequentially: this prevents from excessive disk seeks.
but as you mentioned in another thread, your solution is locked to a single architecture, and I cannot afford that.
But BDB offers tremendous speed, so it won't be easy to decouple the DB engine from the application process.