Maybe you could benefit of using sqlite3_unlock_notify()? See more
info here: http://www.sqlite.org/c3ref/unlock_notify.html.


Pavel

On Fri, Aug 7, 2009 at 1:45 PM, Nikolaus Rath<[email protected]> wrote:
> Hello,
>
> I have program that continuously runs several threads (about 4 to 10)
> which concurrently read and write to an SQLite database. From
> http://www.sqlite.org/sharedcache.html it seems to me that I should be
> using shared cache mode.
>
> Until now, I have set the busy timeout to 500 msec and never had to deal
> with SQLITE_BUSY errors. However, there seems to be no corresponding
> function for the SQLITE_LOCKED errors that are generated in shared cache
> mode. So I changed the code manually sleep for a random amount (0 to 100
> msec) and then try to execute the statement again if it encounters
> SQLITE_LOCKED. But now the threads are often waiting for more than 1
> second before they finally get their query executed.
>
> I suspect this is because the random sleep is wasting a lot of time,
> while without shared cache (and with enabled busy timeout) a thread
> blocks and gets revived as soon as the lock on the database is
> released.
>
>
> How can I avoid this problem? Is there a way to set a busy timeout for
> SQLITE_LOCKED as well? Or a more clever method instead of sleeping for
> random amounts? Or should I just avoid using shared cache mode?
>
>
> Thanks,
>
>
>   -Nikolaus
>
> --
>  »Time flies like an arrow, fruit flies like a Banana.«
>
>  PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6  02CF A9AD B7F8 AE4E 425C
>
>
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