Of the embedded databases I'm familiar with, Berkeley DB with its transaction layer does support multi-process access. It requires some careful coding but does

Of the embedded databases I'm familiar with, Berkeley DB with its transaction layer does support multi-process access. It requires some careful coding but does work and detects deadlocks of the type you describe (http://www.oracle.com/technology/documentation/berkeley-db/db/gsg_txn/C/introduction.html#multithread-intro http://www.oracle.com/technology/documentation/berkeley-db/d...). No idea if this works with language bindings other than the officially-supported C, C++, and Java.