Conceptualizing Threading

JonathanB doulos05 at gmail.com
Thu Jun 21 17:03:22 CEST 2007


> You described how threads introduce a problem in your program -- that of
> generating a sequence of sequential identifiers -- but you didn't describe
> the problem that threads are solving in your program.  Maybe you don't
> need them at all?  What led you to threading in the first place?
>
> Jean-Paul

Well, the problem I thought they would solve is ensuring everyone got
a sequential number. But I suppose they wouldn't solve that, since
from what I gather thread access is somewhat arbitrary. So then, here
is the crux of the issue. Worst case scenario, this program could be
accessed by 5-10 people at a time and I need each one to have the
current information. There are two places I know of that there might
be multi-access problems.

1) This program is so that we can track one team passing assignments
to another. Right now I have the names of everyone in team 2 in a
list. People from team one launch this program and the program grabs a
pointer (stored in a separate file). If person A launches the program
and person B launches the program before person A assigns an order,
they will both have the same pointer, so both orders will go to the
same person.

2) Each assignment has a distinct identifier, which increments by 1
for each assignment (SR001001, SR001002, etc). Either these can be
assigned manually (the current method), or they can be assigned
automatically. If they are assigned manually, I need a way to show
them the most recent number (that would be easy), if they are assigned
automatically I need a way to save the number and pass the incremented
number along (just like the pointer). But I have the same problem here
as above. If two people launch the program at roughly the same time,
they will pull the same data. Since these assignments tend to come in
spurts, concurrent access is likely to be a problem.

So, given those parameters (the rest of this program is a breeze,
there's a class for each person on Team 2 and the class holds some
info about them and a dictionary of assignments with the assignment
number for the key and a value of [assigner, numberAssigned], the only
other tricky thing for me has been logging because I've never had to
do much of it before), how can I prevent these problems? The only
thing that jumps out at me is a server/client model where a server
runs and compiles all the entries, spitting back the result to each
individual client. That way, all the working code lives in the server,
ensuring that the working thread always has the right information,
while the clients only pass data between the user and the server. But
I guess that isn't technically multi-threading is it.




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