I'm not quite sure, but I think I'm pretty careful of sharing objects between threads.
1st, I only cached as few as possible orm objects. I tried to detach them, but I found that if I detach them, I can't access any of their fields any more. 2nd, I create new orm objects based on client request, pass them to class Database and then merge them to scoped sessions, change, commit and then discard these objects. 3rd, I switch to sqlite frequently to check if there is any database operation outside Database, because sqlite doesn't allow multi-thread access. Actually it seems to work until 2 or 3 days ago suddenly cases hang the server. Ah, as I've already written lots of code in ORM, I think maybe I should try to change Database to use a dedicated thread to handle all database operations. That might be a bottle neck of my application, but I really can't give up orm as these mapper classes are used everywhere in my application. On Mar 4, 7:26 pm, 一首诗 <newpt...@gmail.com> wrote: > Hi, all > > I am using sqlalchemy in twisted in my project in the way below. > Defer any database operation so the twisted's main thread won't be > blocked. > > And I use scoped_session, so that sessions won't have to be created > again and again. > > ====================================== > class Database() > def __init__(self, conn_str): > self.conn_str = conn_str > self.engine = create_engine(self.conn_str, echo=False) > self.Session = scoped_session(sessionmaker(bind = self.engine, > expire_on_commit=False)) > > def getObjectById(self, klass, id): > return threads.deferToThread(self._getObjectById, klass, id) > > def _getObjectById(self, klass, id): > sess = self.Session() > return sess.query(klass).get(id) > ====================================== > > The code doesn't work. When I limit the thread numbers to 1 > > reactor.suggestThreadPoolSize(1) > > Everything goes fine. Other wise the server would be blocked and must > be killed by "kill 9 ...". > > The result conflicts with my understanding of sqlalchemy. Since I > don't share any object between threads, there should be no problem! > > Ah.... It always have risk to use something you haven't tried > before .... --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@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 -~----------~----~----~----~------~----~------~--~---
