Thank you very much for the detailed explanation. Now i understood the concept.
> On November 28, 2018 at 8:16 PM Keith Medcalf <[email protected]> wrote: > > > > The difference is that if both threads call the library on the same > connection at the same time (that is, two calls are into the library are > active at the same time) then all hell will break loose. You application will > fail. Memory will be corrupted. You database will be corrupted. Hell may > freeze over. Under no circumstances whatsoever must you *ever* allow this to > happen. > > SQLITE_OPEN_FULLMUTEX (the default) means that Sqlite3 will, each time you > make a call into the library, spend a few CPU cycles to ENSURE that you do > not break the rules and that the consequences described above will not happen. > > SQLITE_OPEN_NOMUTEX (not the default) means that Sqlite3 WILL NOT, each time > you make a call into the library, spend those few CPU cycles ensuring that > you have not broken the rules because YOU have explicitly taken > responsibility upon yourself to ensure that you do no break the rules. > However, if you do break the rules, then you have obviously intended that the > described consequences should come to pass and when they do, they should have > been expected. > > You can also compile the code so the default is SQLITE_OPEN_NOMUTEX and turn > on a special idiot mode that will simply crash (fail an assert) if you break > the rules, rather than letting the aforesaid consequences happen. This takes > more CPU cycles that having "pure" SQLITE_OPEN_NOMUTEX and less that > SQLITE_OPEN_FULLMUTEX. > > So you get to choose the level of consequence and risk that you are willing > to tolerate. > > So, if you have no mutex and two threads use the same connection to update > the same table, then either both will work or you will suffer the > consequences described above. If you use the default serialized (full mutex) > then both will work and there will be no consequence as described above. In > both cases neither operation will be isolated in any way from the other (that > requires using separate connections). > > --- > The fact that there's a Highway to Hell but only a Stairway to Heaven says a > lot about anticipated traffic volume. > > > >-----Original Message----- > >From: sqlite-users [mailto:sqlite-users- > >[email protected]] On Behalf Of Prajeesh Prakash > >Sent: Wednesday, 28 November, 2018 07:16 > >To: SQLite mailing list > >Subject: [sqlite] SQLITE_OPEN_FULLMUTEX vs SQLITE_OPEN_NOMUTEX > > > >Hi Members, > > > >Can any one please give a clear idea about SQLITE_OPEN_FULLMUTEX and > >SQLITE_OPEN_NOMUTEX because i am totally confused with the concept. > >If we enable FULLMUTEX what will happen if two thread trying to > >update the same table (Both thread are from same DB connection) in > >case of NOMUTEX what is the flow > > > > > >Thank you > >_______________________________________________ > >sqlite-users mailing list > >[email protected] > >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > > > _______________________________________________ > sqlite-users mailing list > [email protected] > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list [email protected] http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
