> According to documents, sqlite_busy will happen if new reader cannot get
> > shared_lock or new writer cannot get reserved_lock. > > I didn't see sqlite_busy error from my application. > > I didn't understand this. "database is locked" is SQLITE_BUSY. > Thanks for clarification. I assumed the error message of error code SQLITE_BUSY is something like "databased is busy". > > > Does this mean I need to close the current database connection before I > can > > make the next connection to same database file even through they are not > > shared? > > No, you can have several connections in one thread if you want. > > > Though it is not shared, it seems there may be cases where more > > than 1 database connections are held (in nested function calls). Will > this > > cause any issue? > > This can definitely be the issue. Consider this scenario: > - open connection 1; > - start executing some query on connection 1 - call sqlite3_step() but > it didn't return SQLITE_DONE yet; > - open connection 2; > - execute some update/insert/delete on connection 2 > > In this case you have active statement on connection 1 that holds > SHARED lock on the database. And it will prevent any other connections > from writing. So connection 2 cannot obtain EXCLUSIVE lock, you get > SQLITE_BUSY without any chances to succeed. > Very good point. It seems one connection per function can be error prone. One long-lived connection per thread might be better. Another newbie question. Is it safe for 2 threads to share 1 connection when the connection is protected by my own mutex? Thanks a lot. > > Pavel > > On Wed, Mar 17, 2010 at 1:35 PM, imin imup <imini...@gmail.com> wrote: > > Thanks for help. As a novel sqlite user, it seems I need more. > > > > According to documents, sqlite_busy will happen if new reader cannot get > > shared_lock or new writer cannot get reserved_lock. > > I didn't see sqlite_busy error from my application. > > > > My usage is that: > > single process, multi-thread, multi-database files > > > > multi-database files > > I divided the tables into 2 database files to "increase" concurrency. A > > thread may open two database file at same time, but two database never > > appear in one sql statement. Is this likely to cause any issue? > > > > about "one connection per thread" > > Does this mean I need to close the current database connection before I > can > > make the next connection to same database file even through they are not > > shared? > > I tend to use short-lived database connections locally defined within > each > > function. Though it is not shared, it seems there may be cases where more > > than 1 database connections are held (in nested function calls). Will > this > > cause any issue? > > > > On Wed, Mar 17, 2010 at 11:05 AM, Pavel Ivanov <paiva...@gmail.com> > wrote: > > > >> http://www.sqlite.org/faq.html#q5 > >> http://www.sqlite.org/lockingv3.html > >> > >> Pavel > >> > >> On Wed, Mar 17, 2010 at 11:46 AM, imin imup <imini...@gmail.com> wrote: > >> > Hello users, > >> > > >> > I'm using sqlite 3.6.12 in muti-threaded application. I'm getting > sqlite > >> > errors occasionally. > >> > The error message is > >> > > >> > *sqlite error: database is locked* > >> > > >> > could someone explain to me what happened and what to be done? or > point > >> me > >> > to a document on how to fix this? > >> > > >> > Best > >> > > >> > Imin > >> > _______________________________________________ > >> > sqlite-users mailing list > >> > sqlite-users@sqlite.org > >> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > >> > > >> _______________________________________________ > >> sqlite-users mailing list > >> sqlite-users@sqlite.org > >> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > >> > > _______________________________________________ > > sqlite-users mailing list > > sqlite-users@sqlite.org > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
