For any select that takes place within a transaction, Postgres by default automatically acquires a access share lock on the involved tables, so this should be happening on all requests. However, access share locks do not conflict with each other, so I don't think these locks are necessarily the source of your problem.
Anthony On Thursday, April 5, 2018 at 10:58:07 AM UTC-4, Lisandro wrote: > > Hi there! This is somehow related to this other topic [1], which I have > closed because I've found some new evidence and I though it would be better > to open a new topic. > > I'm having this problem where a simple select on auth_user table hangs > indefinitely, until timeout. > The problem occurs in one specific user account. The user logs in, but > after the successfull login, any request hangs. > I checked the postgres long running queries and I see this query hanging > until timeout: > > SELECT auth_user.id, auth_user.first_name, auth_user.last_name, auth_user. > email, auth_user.password, auth_user.registration_key, auth_user. > reset_password_key, auth_user.registration_id, auth_user.alta,auth_user. > plantel, auth_user.responsable, auth_user.nombre, auth_user.telefono, > auth_user.autor, auth_user.foto, auth_user.foto_temp, auth_user.moderador, > auth_user.descripcion, auth_user.facebook,auth_user.twitter, auth_user. > linkedin, auth_user.gplus FROM auth_user WHERE (auth_user.id = 2) LIMIT 1 > OFFSET 0; > > > As you see, the query is a simple select to the auth_user table. Also, > notice that it uses LIMIT, so it retrieves one only row. > Additionally, I can confirm that the table has only four rows. > > I went a little further, and I checked the pg_locks at postgres when the > problem is happening (that is, during the 60 seconds until timeout). > This is the query I run to check the locks and this is what I see during > that time: > > select t.relname,l.locktype,page,virtualtransaction,pid,mode,granted from > pg_locks l, pg_stat_all_tables t where l.relation=t.relid order by > relation asc; > > > relname | locktype | page | virtualtransaction | pid > | mode | granted > > -----------------------------+----------+------+--------------------+------+-----------------+--------- > pg_class | relation | | 70/908027 | 4421 > | AccessShareLock | t > pg_index | relation | | 70/908027 | 4421 > | AccessShareLock | t > pg_namespace | relation | | 70/908027 | 4421 > | AccessShareLock | t > web2py_session_infosanpedro | relation | | 16/1858255 | 9865 > | AccessShareLock | t > auth_user | relation | | 16/1858255 | 9865 > | AccessShareLock | t > (5 rows) > > > *Notice the lock of the web2py_session_* and auth_user tables.* > *That lock is there during the whole 60 seconds, until timeout*. > > After timeout, the lock isn't there anymore. > If I reload the page, again, the lock appears and the request hangs until > timeout. > > All the other user accounts can login normally. > Also, there is nothing particularly different with the user account having > the problem (it's an account like any other else). > Of course, I already tried to delete everything from the web2py_session > table, but it doesn't work, the problem remains. > > Where else should I look? > Would it help if I share with you the app code for the login? It doesn't > do any tricky stuff. > What concerns me is that the problem is generated in one specific account, > but in several of our customers (we have the same web2py app installed for > every one of our customers, each one has its own database). The same > problem is happening randomly in a few accounts. Database activity is > really low. > > I'm pretty lost here, so any help or suggestion will be appreciated. > Thanks in advance. > Regards, > Lisandro > > > [1] https://groups.google.com/forum/#!topic/web2py/o0FBeimrr5c > -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
