RE: [ZODB-Dev] ZEO ClientStorage's use of the asyncore main loop(was [Fwd: Re: [Zope3-dev] Twisted Publisher and Zope 2])
[Jim] > Historical note: asyncore didn't support private event loops either until > I added the extra argument to the constructor. I'm not sure why you need > to pass the map to anything but the constructor. Oddly. most, but not > all of the methods that take a map, default to the one set in the > constructor. I don't really remember the details AFAICT, in 2.4.2 all asyncore _methods_ default to the map passed to the constructor. This isn't always dead obvious, but it's never truly subtle; e.g., this is as bad as it gets: def set_socket(self, sock, map=None): self.socket = sock self._fileno = sock.fileno() self.add_channel(map) The only trick there is that if you don't pass map= to set_socket(), it passes None on to add_channel(), and add_channel() then uses self._map. The asyncore _functions_ are a different story, but I suppose they have to be. You do have to pass a map to poll(), poll2(), loop() and close_all(), else they'll use the module global socket_map. But they aren't methods, so have no way to know any better. Also, AFAICT, this is all equally true in 2.3.5's asyncore. It's OK to stop being afraid of bad code in Python 1.5.2 ;-) ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
RE: [ZODB-Dev] ZEO ClientStorage's use of the asyncore main loop (was[Fwd: Re: [Zope3-dev] Twisted Publisher and Zope 2])
[Jim Fulton] ... > > 2. The ZEO client storage doesn't work optimally if there isn't a > main loop. In particular, without an asyncore main loop, a > ZEO client storage won't see messages from the ZEO server until > the client storage tries to read or write some data from or to > the ZEO storage server. Just FYI, in "current" ZODB this is probably less of an issue than it used to be, since Connection now implements ISynchronizer and sets up Connection. _storage_sync() as its ISynchronzizer afterCompletion() and newTransaction() methods. Maybe that's one reason you didn't see as much damage in current Zope3 as it may have been possible to imagine ;-) ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO ClientStorage's use of the asyncore main loop (was [Fwd: Re: [Zope3-dev] Twisted Publisher and Zope 2])
Shane Hathaway wrote: Jim Fulton wrote: Tim and I have discussed this for some time. We think an asynchronous I/O approach is still appropriate, to handle asynchronous messages from servers to clients, but we need to get away from expecting a server to provide the asyncore main loop needed by ZEO. Rather, ZEO should provide its own main loop running in a separate thread. (Or, possibly, each client storage should have its own thread.) Among other things, this would allow us to get rid of the horribly complex dual-mode code we have now. I think that's a good strategy. (Note that we've had lots of frustration with asyncore. It is tempting to get rid of that at the same time. However, we still need an asynchronous I/O framework. This would probably requite a switch to Twisted. This might be worthwhile, but would almost certainly entail a lot of risk. I'm not at all sure the benefit is worth it unless there were some able volunteers who wanted to work on it.) Last I checked, Twisted could not support a private event loop. Twisted assumes there is only one event loop for all threads. I'd like to know if this has changed. The asyncore module can support a private event loop, although it's ugly--you have to pass the 'map' argument all over the place. Historical note: asyncore didn't support private event loops either until I added the extra argument to the constructor. I'm not sure why you need to pass the map to anything but the constructor. Oddly. most, but not all of the methods that take a map, default to the one set in the constructor. I don't really remember the details Jim -- Jim Fulton mailto:[EMAIL PROTECTED] Python Powered! CTO (540) 361-1714http://www.python.org Zope Corporation http://www.zope.com http://www.zope.org ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO ClientStorage's use of the asyncore main loop (was [Fwd: Re: [Zope3-dev] Twisted Publisher and Zope 2])
Jim Fulton wrote: Tim and I have discussed this for some time. We think an asynchronous I/O approach is still appropriate, to handle asynchronous messages from servers to clients, but we need to get away from expecting a server to provide the asyncore main loop needed by ZEO. Rather, ZEO should provide its own main loop running in a separate thread. (Or, possibly, each client storage should have its own thread.) Among other things, this would allow us to get rid of the horribly complex dual-mode code we have now. I think that's a good strategy. (Note that we've had lots of frustration with asyncore. It is tempting to get rid of that at the same time. However, we still need an asynchronous I/O framework. This would probably requite a switch to Twisted. This might be worthwhile, but would almost certainly entail a lot of risk. I'm not at all sure the benefit is worth it unless there were some able volunteers who wanted to work on it.) Last I checked, Twisted could not support a private event loop. Twisted assumes there is only one event loop for all threads. I'd like to know if this has changed. The asyncore module can support a private event loop, although it's ugly--you have to pass the 'map' argument all over the place. Shane ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO ClientStorage's use of the asyncore main loop (was [Fwd: Re: [Zope3-dev] Twisted Publisher and Zope 2])
Jim Fulton wrote: Here is a draft of a note I plan to send to the zodb list soon: Sigh, I meant to take this line out. :) Jim -- Jim Fulton mailto:[EMAIL PROTECTED] Python Powered! CTO (540) 361-1714http://www.python.org Zope Corporation http://www.zope.com http://www.zope.org ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
