Any penalty to using one big cluster in a state machine?

Question

I've been working on a lot of small/medium sized state machines lately, and I've gotten into a habit of putting most of my data (single values, arrays, strings, even LVOOP objects) in one cluster that I pass from state to state with a shift register.  I just unbundle the data I need in each state, work on it, and bundle it back in for the next state.  Part of me says that this is a bad idea - that I should separate the big cluster into a set of smaller clusters that group the data by logical categories.  Another part of me says that if I do it that way, I'm just creating needless clutter on my diagram.
So my question is simply this - is there any significant performance penalty for using a single cluster rather than multiple clusters in this fashion?  I never run the whole cluster into subVIs, and I never split the main cluster wire, so it doesn't seem like there should be... but I've been wrong before!
Thanks,
Jason

Answer 1

As Norbert mentioned, the answer to your Q is dependant on your data structure. Provided you can do all of your data manipulation "in-place" there should not be any issues. The more complex structures can still be handled "in-place" but you may have to use the in-place operations to achieve this effect. Depending how comfortable you are with those operators, they can complicate the appearence of our code.
If you can'y do everything "in-plcae" and you have a Super-Cluster, then its time for me to Quote Rolf again when he wrote "Once all of you physical memory is filled up with a single cluster, your application is probably going to suck."
So lest say you have cleared all of the above hurdles and still want to use a single SR that has all data for all states. I ask you to carefull examine where the app may go in the future and what type of animal it could turn into. if there is even a small chance that app may turn into something that non-computer users will use (requires robust app to prtect itself from dumb users) the single cluster approach is going to get in your way when the app gets big.
1) If you have to add another field to the cluster, every function that uses that cluster should be re-tested. WE have an app in-house that was developed by our customer and we support. There is an 800+ step proceedure required to re-verify the app!
2) AS more functionality is added you will add more states to your state machine. Personally, I cringe when I see the support developer have to choose from a list of 300 states when working with the Stae machine.
3) You will have a hard time re-using code aside from cutting-n-pasting
4) When you unbundle manipulate and replace, you are in danger of creating duplicate data which will impact performance.
I never went through the formal IS training but my wife did and she has given me the short version to learn how to normalize a DB. There is actually a science to the process that results in only related items being grouped together and if you take to the full exdtreme of "fully Normalized DB", there absolutely no duplicates of data. For LV apps a Fully Normalized DB adds some overhead so I don't go that far.
THe following will ignore using an Object Oriented approach and stick with old-school ideas.
So after I analyze my data structures and group related items together and review who touches what when, THEN I try to wrap-up the data in Action Engines. More often than not, the action will replace some or most of the work done in some states. From your Q it sounds like your "read-mod-replace" constructs can be moved into AEs with little effort.
Now for OOP
I'm still learning OO system design but I have found myself "turning my apps inside out" with LVOOP. By this I mean rather than think that the data AND the function are inside the AE, the data is outside and acted on by what is inside the LVOOP methods. I have been amazed at the degree to which LVOOP can operate in-place, but I digress. There is some arguement/design pattern that says that if you have a function like a test that uses other classes, then you can create a class for the test and slam all of the required object into you need.
Done rambling for now. As usual, if there is anyone out there that want to correct me any of the above, please do so!
Ben
Ben Rayner
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