[Zope] Survey: Gadfly usage

[Aaron Watters]

> Regarding thread safety. Aaron has indicated he will look into this,
> but for the moment, mutexes would need to be used. Like most of us,
> Aaron has a full time job and little free time. Since Gadfly is open
> source, perhaps Aaron would accept volunteer efforts to tackle threads?

Unfortunately this is a very tricky issue with difficult to anticipate side-effects
all through the engine.  I don't recommend it especially since it would be sufficiently
different from the current engine to constitute essentially a new implementation.
I have been thinking about a new implementation that would support (limited)
threading in the same engine.  This is somewhere in the future.

For now I don't see why you can't simply guard each gadfly database instance
by a mutex and thus serialize access to the database.  I would even recommend
this for other database engines since otherwise it might be possible for two
threads to deadlock/livelock waiting for the same data item locks in the data engine
to clear.  I've seen this problem even with CGI scripts at client sites.
[This is another problem that tends to only show up when the system is heavily
loaded under real use :)]

   -- Aaron Watters

===

Jim Ahlstrom's catch 22 correlary:
   "If you think you are smart enough to write multithreaded programs,
    you're not."