You might want to use the Berkeley DB instead of the FileCacheLoader. There's also a JDBM implementation (I wrote :-) ) that might be adequate.
Or, create a "deeper" tree where there are fewer children per node. E.g. if you were to create a phone book, instead of just dividing the entries by "A, B, C" etc., further divide them into "AB" "AC" etc.
Does the JDBM implementation support multiple processes writing to a file?
thanks in advance,
I might have misunderstood you. If you have multiple _processes_ (not threads) doing writes to a file, you need some sort of central coordinator, and that would require you to use a traditional RDB. JBCache does support JDBC databases.