Monday, December 10, 2007

studying a complex batch app (WallSt) -- suggestions

Challenge: too many steps. Each usually represented by a function if well-modularized.
! Challenge: You don't know how many of the steps are usually skipped and deserve no scrutiny.
Challenge: too many business rules
Challenge: too much branching including return/break/continue
! Challenge: Each run of the batch takes too long. run-edit-analyze cycle too long.

- Tip: identify and put aside "quick" steps in order to focus on the important steps. Subs that take a short time are usually less complicated or involve less database interaction.
- Tip: real benchmarking (or reverse engineering in general) requires good test data.
- Tip: initially, perhaps you prefer just a single record in input stream.
- Tip: if possible, output all the sql statements. If possible, Also "annouce" entry and exit of key functions, which provide context to the sql statements.
- Tip: identify non-essential yet slow steps to comment out. Non-essential = zero downstream impact
- Tip: At a key junction in an important function, when you print out a variable it's immensely useful to see the call stack too.
- Tip: rename variables/functions -- one of the safest and reversible changes (with perhaps one major side effect ie cvs diff prove ...)

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