Wednesday, June 2, 2010

Change Tactics

Given a problem, there are generally several ways to approach it. The problem might be an issue occurring at a customer site, or a test we want to conduct, or a scaling design goal, etc. In any of these situations, we have lots of choices in how we tackle it. We might start by looking at what changed to cause the issue to occur. We might begin with reviewing the architecture of massively scaling services similar to ours. We might use code review to identify possible flaws that we want to exercise with unit testing code.

All those are great, and worth trying.

But what if it's not working?

Is that "what changed?" question you've been asking yourself about a problem that showed up at a client site not getting you any answers? Did that massively scalable architecture that seems like it would provide some good ideas lead you down a rathole of trying to map your square peg to their round role?

Time to change tactics. If it's not working, stop doing it, and try something else.

So how do we know when to change it up versus when to pursue a given tactic?

As a rule of thumb, I try to give no more than 20% of my estimate to any given tactic.

Let's say, for example, that I'm designing a test of a new module. If I estimated that the whole test would take me 5 days, and after one day I'm nowhere, it's time to rethink my tactics. If it's only been an hour or two, well, I might just not have taken it far enough yet or given the tactic enough time. If it's been two days and I'm still nowhere, I'm ratholing.

As with any heuristic, there are exceptions. Sometimes it's worth spending longer on a particularly tricky, slow or likely tactic. Just make that a conscious decision. About 20% of the way through your overall estimate, stop. Ask yourself if you're really getting anywhere with this tactic. If not, time to change.

We'd all like our first tactics to work consistently. Often, they will. For those times it won't, pull yourself out of the rathole and change tactics.

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