The doc for mdb_dbi_open says:

* This function must not be called from multiple concurrent
* transactions in the same process. A transaction that uses
* this function must finish (either commit or abort) before
* any other transaction in the process may use this function.

This indicates that each process can only perform one transaction at the same time.

This makes sense for write transactions, but wasn't LMDB supposed to support multiple read transactions at the same time?

I'm a bit confused now. Can you assist?