On 8 May 2016 at 10:14, just_rookie <925345468 at qq.com> wrote: > Obviously, I did not do incompatible things with a database at the same > time. >
You are attempting to drop a table in databases 300_500.db and 600_900.db. Obviously another process must create that table, since your test code isn't. Dropping a table involves writing to the database. To write the database it must be locked. If another process already has a write-lock your MPI tasks won't be able to obtain one and will fail with "database is locked". If another process is holding a read-lock, your MPI tasks will obtain a write-lock but won't be able to COMMIT until the read-lock is relinquished. If you're getting "database is locked" even with a busy timeout of 10 seconds, you have something other connection to the DB holding on to a lock. It could be that your other code is not calling sqlite3_finalize on every sqlite3_stmt, or you just have long running transactions. -Rowan
