Do you have any transactions that look like: BEGIN SELECT INSERT/DELETE/UPDATE COMMIT
If you do, you may have multiple threads trying to escalate from a SHARED to a RESERVED lock as described here: http://sqlite.org/capi3ref.html#sqlite3_busy_handler It's important that if you have multithreaded access and a strategy that involves either retrying or waiting on SQLITE_BUSY that you specify at the beginning of write transactions that the transaction requires a higher level lock. I do this using "BEGIN IMMEDIATE". The thread currently on this list with subject "[sqlite] BEGIN and Backup [was [sqlite] Problems with multiple threads?]" Discusses a similar issue. Pat -----Original Message----- From: Jiri Hajek [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 07, 2006 9:26 AM To: sqlite-users@sqlite.org Subject: RE: [sqlite] Problems with multiple threads? Thanks for an additional explanation, I used sqlite3_get_autocommit() for debugging and it helped me to find out that it really was my fault. There was an incorrect processing after COMMIT returned SQLITE_BUSY. So sorry for this. However, right after fixing this, I found another problem. It certainly can be my fault, but I don't see how could it be: If I don't use transactions, multiple threads seem to proceed well, but then right after I add BEGIN and COMMIT to some place, all threads lock eventually. I debugged it and found that _all_ threads accessing SQLite are in a loop waiting for an action to proceed and all of them keep getting SQLITE_BUSY result. I wonder, can it be somehow my fault, or is it some kind of a dead-lock in SQLite? In the simpliest form it takes only two threads to reproduce and the problem looks like: Thread 1: BEGIN TRANSACTION <-- proceeded INSERT INTO ... <-- Processing stops here, waiting in a loop, Sqlite3_step() infinitely returns SQLITE_BUSY COMMIT Thread 2: // no explicit transaction start here DELETE FROM ... <-- Processing stops here, waiting in a loop, Sqlite3_step() infinitely returns SQLITE_BUSY Thread 2 can also look like this in order to reproduce the problem (situation in Thread 1 remains the same): BEGIN TRANSACTION <-- proceeded DELETE FROM ... <-- proceeded COMMIT <-- Processing stops here, waiting in a loop, Sqlite3_step() infinitely returns SQLITE_BUSY No other thread calls any SQLite function. Do you have any idea what could be wrong? Thanks, Jiri
