Your advice sound reasonable. That means I have check the transaction **before** the hanged commit, maybe I forgot to commit or close a session at that time.
On Jan 31, 7:55 am, Gunnlaugur Briem <gunnlau...@gmail.com> wrote: > You probably don't have to add locks in your code. The database system > takes locks on behalf of your code (in operations initiated by your > code) as necessary to ensure transactional consistency. That's one of > the benefits of an RDBMS. > > What you do have to do is to make sure that those database locks don't > stay around forever (blocking other transactions). That happens when > you forget to complete (commit or rollback/close) the transaction that > creates them. If it eventually completes (either way), then things > will work fine for the most part --- and at least not hang. > > (There is a lot more to this; you should read up on transactions and > locks, it's fascinating stuff. But your immediate problem is very > likely just a session/connection that you forget to close.) > > Regards, > > - Gulli > > On Jan 30, 4:53 am, 一首诗 <newpt...@gmail.com> wrote: > > > Yeah， there might be another transaction modifying the same data > > (actually the same line of data in database). > > > But I didn't expect that might cause problem before! > > > Oh, if that's true, then I have to add some lock in my code to avoid > > that. That's a big problem. > > > On Jan 29, 10:13 pm, Alex Brasetvik <a...@brasetvik.com> wrote: > > > > On Jan 29, 2010, at 15:01 , 一首诗 wrote: > > > > > What might cause this kind of problem? > > > > Possibly waiting on locks. Do you have any concurrent transactions > > > modifying the same data? > > > > When the problem appears, run `select * from pg_stat_activity` to see > > > whether there are locking issues. > > > > To see the locks involved, run `select * from pg_locks`. > > > > -- > > > Alex Brasetvik -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
