Milosz Tanski wrote:

I saw that LMDB recently added a new flag MDB_NOLOCK. Is there a way to keep the reader lock file and but do away with the write lock?

My motivation for doing this to be able to use LMDB from a process that forks to share the database. And the application can implement it's own write lock (mutex in shm or futex on linux).

What advantage do you gain from using your own write lock?

Note that forking to share the database is explicitly *not* supported.

This would be preferable to having to do doing something like a MDB_NOLOCK with a pthread_rwlock since we could still have parallel readers with one writer.