> Further more, at the end of this post (http://www.sqlite.org/ > whentouse.html), it mentions sqlite uses reader/writer lock. So here > comes my first question, perhaps mainly for Massimo: When a user click > on our web2py app which contains a db=SQLDB("sqlite://mydb.sqlite"), > does that mean we already open the db, create a transaction, therefore > the whole sqlite db is locked by writer lock, until the current user > request is finished?
Yes > If so, that means even two crud.read() request > can not be served at the same time. True. They will be serialized in sqlite. > By the way, this post (http://www.sqlite.org/threadsafe.html) mentions > three thread modes of sqlite. Do you know which mode is python 's > built-in sqlite uses? Is it the "default Serialized mode"? If so, that > means even two crud.read() request can not be served at the same time. I think that is it. > Thanks in advance for any feedback. > > Sincerely, > Iceberg > > On Apr2, 7:50pm, Beerc <berces.las...@fomi.hu> wrote: > > > Seehttp://stackoverflow.com/questions/54998/how-scalable-is-sqlite > > > [...] there is nothing that prevents using an Sqlite database in a > > multi-user environment, but every transaction (in effect, every SQL > > statement that modifies the database) takes a lock on the file, which > > will prevent other users from accessing the database at all. > > > So if you have lots of modifications done to the database, you're > > essentially going to hit scaling problems very quick. If, on the other > > hand, you have lots of read access compared to write access, it might > > not be so bad. > > > On Apr 2, 12:00 pm, Sven <svenstrin...@gmail.com> wrote: > > > > Hi, > > > > I programmed a psychological experiment in flash and store answers/ > > > results in a sqlite database using web2py (behind nginx server + > > > fastcgi) and pyamf. Everything seems to be all right when I test it, > > > but with as few as 2 simultaneous users I (sometimes) run into > > > trouble. A try with seven simultaneous users resulted in only 2 > > > succesfully stored experimental data.sets > > > I find it very hard to debug, since there are no tickets in web2py. > > > Flash does sometimes produce a remoting error in that situation, but > > > without too much information. > > > > I seems to me there is some kind of concurrency problem, but I assumed > > > web2py/sqlite would take care of that for me. Or should I explicitly > > > deal with this? Explicitly commit, check if inserts and updates were > > > successful and if not try again? > > > > Any suggestions, comments ideas would be really appreciated. > > > > Thanks. > > > > Sven -- You received this message because you are subscribed to the Google Groups "web2py-users" group. To post to this group, send email to web...@googlegroups.com. To unsubscribe from this group, send email to web2py+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/web2py?hl=en.
