Jiri Hajek wrote:
> Hello,
>
> I'm trying to use SQLite in an application where it's needed to work with
> one database in mutliple threads. Based on all the info I read in SQLite
> documentation I create a new database connection for every new thread
> created. Each thread does some SELECTs, INSERTs or UPDATEs, but there isn't
> any schema modification. If multiple threads are running, I encounter some
> strange problems:
>
> 1. Occasionally after running Sqlite3_step() I get SQLITE_CANTOPEN ('Unable
> to open the database file') error. I found out that it can be fixed by
> running the query again, i.e. again calling Sqlite3_Prepare(). So this isn't
> a big issue, but still I wonder why this error message is returned?
> Shouldn't SQLITE_BUSY or SQLITE_LOCKED be returned instead?
>
> 2. More serious issue is that after I enable transaction usage (not used in
> 1.) sometimes (again, it's random) after calling 'BEGIN TRANSACTION' I get
> an error SQLITE_ERROR ('cannot start a transaction within a transaction').
> Problem is that I definitely am not already in a transaction. The only
> reason for this seems to be that there's >1 thread running, with only 1
> thread running there's no problem.
>
> I tried this also with the latest version of SQLite (3.3.6 on Windows).
>
> Any idea what can I do about it?
>
> Thanks,
> Jiri
>
>
>
I've seen these same issues myself too on linux/3.3.5, my solution was
using our own internal classes to marshal read/write locking ourselves.
Cleared everything right up.
--
Bill King, Software Engineer
Trolltech, Brisbane Technology Park
26 Brandl St, Eight Mile Plains,
QLD, Australia, 4113
Tel + 61 7 3219 9906 (x137)
Fax + 61 7 3219 9938
mobile: 0423 532 733
