Steve Holden <[EMAIL PROTECTED]> writes: > catsup wrote: >> Hi, >> I have an app written under version Python 2.3.5. The problem I'm >> having is that it hangs on one of its threads. The thread that hangs >> does updates to a standard dictionary shared with another thread that >> only reads this dictionary. This app works beautifully on a single >> processor boxes in my testing environment, but this problem quickly >> occurs when the software runs on a dual cpu SMP blade server with >> hyperthreading turned off, Windows 2003 server. >> > I don't see why you should get problems on SMP hardware, since the > threads are all part of the same process and should therefore (I'd > have thought) be tagged with the same processor affinity. Hence the > GIL should manage contention successfully. > >> I do not bother using application level locks because I figure the GIL >> is going to do the job for me, and because with one thread doing >> updates and the other only reading, things remain consistent logically >> for the app. The app will not have a problem if the dictionary changes >> just before it does a read. >> > I believe dictionary access is an atomic operation wrt thread > switches anyway, so I'm (again) not sure why a thread is hanging.
Well, there's at least the 'do not mutate a dictionary (or list) while iterating over it' advice. Having one thread writing and another reading makes it IMO impossible to avoid the conflict. Thomas -- http://mail.python.org/mailman/listinfo/python-list
