Thanks for your clarification.
---------------------------------------- > From: [email protected] > To: [email protected] > Date: Mon, 9 Feb 2015 07:18:29 +0000 > Subject: Re: [sqlite] Multi-thread mode question > > In serialized mode, SQLite will acquire the mutex when it detects you are > "starting to use" the database handle (somewhere between entering > sqlite3_prepare and the first sqlite3_step) and then HANG ON TO IT, NOT > LETTING GO until the calling thread is "finished" (like when sqlite3_step > returns SQLITE_DONE or the thread calls sqlite3_reset or sqlite3_finalize). > > In multithread mode, you are taking over this responsibility; if you take > care, you may nest several selects from different threads into a single > transaction, but need to be aware of the fact that they will all commit or > rollback together. > > -----Ursprüngliche Nachricht----- > Von: Neo Anderson [mailto:[email protected]] > Gesendet: Montag, 09. Februar 2015 06:34 > An: General Discussion of SQLite Database > Betreff: Re: [sqlite] Multi-thread mode question > >> Does the application work if you configure SQLite to serialized mode? > Yes. But I am confused why serialized mode works while multi-thread mode > always cause crashes because I also wrap calls around statement handle. > >> even if you wrap the sqlite3_ calls... you'll need to wrap the entire >> lifetime of the statment... > Do I need to do this in serialized mode (suppose I use a single connection > across multiple threads)? > > ---------------------------------------- >> Date: Sun, 8 Feb 2015 03:31:46 -0800 >> From: [email protected] >> To: [email protected] >> Subject: Re: [sqlite] Multi-thread mode question >> >> it's better to use a connection per thread... the connection resource >> isn't very big... >> even if you wrap the sqlite3_ calls... you'll need to wrap the entire >> lifetime of the statment... if you do a execute and then start >> stepping and getting values while another thread starts another >> statement... that's 3 individual locks, but it doesn't lock the >> context of the statement being used... it will lead to bizarre crashes >> in the database; similar to double-releasing memory or delayed >> reference of memory that has been released. >> >> On Sun, Feb 8, 2015 at 3:00 AM, Dan Kennedy <[email protected]> wrote: >> >>> On 02/08/2015 04:30 PM, Neo Anderson wrote: >>> >>>> The doc says: >>>> >>>> Multi-thread. >>>> In this mode, SQLite can be safely used by multiple threads provided >>>> that no single database connection is used simultaneously in two or >>>> more threads. >>>> >>>> I have a scenario that every sqlite3_calls around a single database >>>> connection is protected by a recursive mutex, but I have very >>>> strange runtime error in sqlite3.c and each time the error occurs at >>>> a different place. >>>> >>>> Does this mean the following statement is true: >>>> >>>> In muti-thead mode, a single database connection cannot be shared >>>> among threads even if any activity around the connection is protected by a >>>> mutex. >>>> >>> >>> Not true. >>> >>> The only difference between multi-threaded and serialized mode is >>> that, internally, every sqlite3_xxx() API call grabs a recursive >>> mutex to prevent two threads from simultaneously accessing the database >>> handle structure. >>> i.e. the same thing your code is doing externally. >>> >>> Note that calls on statement handles (i.e. sqlite3_step(), >>> sqlite3_column_text() etc.) count as calls on the database handle >>> that created them. So you need to protect them with the same mutex. >>> >>> Does the application work if you configure SQLite to serialized mode? >>> >>> Dan. >>> >>> >>> >>> _______________________________________________ >>> sqlite-users mailing list >>> [email protected] >>> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users >>> >> _______________________________________________ >> sqlite-users mailing list >> [email protected] >> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > _______________________________________________ > sqlite-users mailing list > [email protected] > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > ___________________________________________ > Gunter Hick > Software Engineer > Scientific Games International GmbH > FN 157284 a, HG Wien > Klitschgasse 2-4, A-1130 Vienna, Austria > Tel: +43 1 80100 0 > E-Mail: [email protected] > > This communication (including any attachments) is intended for the use of the > intended recipient(s) only and may contain information that is confidential, > privileged or legally protected. 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