Is it standard to log each case of a switch statement?

Question

Some code I wrote was sent back to me during peer review, telling me to add logging to the start of each case in a switch statement in a servlet (Java, if that matters), so if something goes wrong, we can see where. I figured that doesn't make sense, as we log entire stack traces anyway, but the response I got to that was

"It's standard practise throughout the entire industry."

They didn't have time to debate, which is fair enough, and I'll do what they say. But this hasn't been my experience in other companies. I just want to know, is it really some kind of standard practise? What is it useful for?

As an example of what I mean:

switch (task) {
    case VIEW:
        logger.info("inside VIEW for taskPage");
        {...}

    case EDIT:
        logger.info("inside EDIT for taskPage");
        {...}

Answer 1

If it is its a bad practice.

I think its fair to say that there is a lot of this kind of 'debug logging' out there. By which I mean logging which enables you to follow the flow of logic through the code.

However, the reason I say that its a bad thing is that:

• Its almost impossible to log enough information to show you the entire flow. You will see people logging the method name and all parameters on each method for example, and still want this kind of conditional branch logging
• Even a small amount of this kind of logging generates huge volumes of logs. Even if you do catch an anomalous situation, finding it will be a nightmare
• It should be possible to follow the logic via really debugging, which gives you far more insight into whats going on that trying to interpret logs.

Instead, try to log things to do (input) and results of things done (output). This allows you to spot unusual outcomes and replay them in an integration test if required.

ie. Log OrderPlaced {orderstate} and OrderProcessed {orderstate}

Avoid logging non errors inside your business logic ie. "reducing price by 2% because its a sale"