Fix or Manage?

Sometimes bugs come along that require significant work to fix. Depending on what project timelines are like at the moment, sometimes fixing the bug isn’t the best option. For example, a race condition in the caching architecture causes pages to be stale. The persistent data store is correct, but the cache is not. To the person who just triggered the update, there’s a bug. The information on the public side is not in sync with the information they just entered.

So, like any other bug, a report will eventually percolate down to the dev team. People scream, fortunes are lost, the svn blame command is used, and the devs who wrote the code pee their pants. Once the chaos dies down, the actual prognosis of this issue can turn out to be extremely grim.

A shortcoming of the caching architecture shows that there’s a race condition when the system is under heavy load. In order to fix it, the dev team needs to plumb the depths of the data access layer, and probably change some parameters. But that’ll probably break everything. Everywhere. Or the layer manipulating the data could be fixed to replace the cache instead of invalidating. Except the methods to manipulate that entity live in 3 different codebases. It’ll probably break the editor. Either way, the actual solution doesn’t matter.The dev team certainly needs to do something, and it needs to be released three days ago.

The correct way to fix this issue will vary widely depending on circumstances. But in this particular case, the best answer was to not fix it, just manage it. Our team was busy, there were other projects that were more pressing. Plus the codebase was being rewritten. So instead of flogging a dead horse, a simple script was thrown together that compared the cache and the database. If they were out of sync, the cache would be cleared, and would be repopulated with the correct information the next time it was requested. Once it was implemented, the bug was still there, but the cache seemed to be up to date.

Every dev team will face bugs that have enormous costs to fix. The way to deal with these bugs will be different every time they come up. It’s important to remember that managing bugs can be almost as effective as fixing them.

1 comment

  1. — December 7, 2012 11:01 pm

    great blog thanks

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