This will block threads while waiting for other threads to write. That might work great for your threading model but I usually end up putting the writer in one thread and then other threads send writes to the writer thread.
First one for writing with flags:
SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE | SQLITE_OPEN_FULLMUTEX
SQLITE_OPEN_READONLY | SQLITE_OPEN_FULLMUTEX