Exactly. In cases where I expect long-running parallel connections from separate processes to the same sqlite file, I make sure that all read transactions do `B

Exactly. In cases where I expect long-running parallel connections from separate processes to the same sqlite file, I make sure that all read transactions do `BEGIN DEFERRED` so `COMMIT` releases the read locks, and all write transactions do `BEGIN IMMEDIATE` so that `SQLITE_BUSY` timeout is not side-stepped. There was one case where all transactions were implemented using nested `SAVEPOINT bla` so `BEGIN IMMEDIATE` could not be used without more hassle, so this ended all “I know I'm going to write” transactions to instantly update a single-row table so that their lock would not begin as DEFERRED and eventually switch to `IMMEDIATE`; this way almost all `SQLITE_BUSY` side-steppings disappeared. (timeout was set to 30 seconds but all read/write transactions were instrumented to have less than 5 seconds duration).