When to log a stacktrace for a caught exception

Question

I recently asked whether to report the getMessage() text of a caught exception. Rather surprisingly, most answers misunderstood my question and thought I was asking whether

Answer 1

I usually report exceptions not related to GUI. GUI Exceptions are common, and in heavy Swing programs usually happens.

Generally speaking, i'm deeply interested in: DB related exceptions, My-own-stupid-errors exceptions (array out of bounds, and stuff like that) and some other things that cannot be handled by me, like WebServices etc.

I think it depends the type of system, if it's a public one (like a website), or if it's private (intranet sites, GUI local)

Answer 2

It's context dependent. For example, I might not log / report a ParseException from NumberFormat when parsing input from an external system, but I would definitely do so if I caught a ParseException which was dealing with data enclosed within the boundary of my system, since this would indicate an inconsistency in internal system state rather than an input value validation falure.

Answer 3

I personally try to obey these rules:

• if I can handle the exception in the catch in a 'recoverable' way (e.g. a DateFormatException), no need to trace the stack

• if I want to rethrow the exception, log no stack trace. (rethrow in a chained way to retain this information)

• if I handle the exception in a catch block as an error case (e.g. sql error), I log the stack trace.

• if it's a runtime exception, I would suggest the framework (yours or whatever you use) does the tracing.

Answer 4

I would report all of them. But if you are using log4j then you can control which ones you know for sure you will not be interested to see in the log. If a particular user exception has a different class, then disable logging in that class in production and enable it in lower environments. In that way, you are not doing anything at the code level for reporting. Its all abstracted at the logging framework.

Answer 5

You - the developer - will need the stack trace if you are in an error situation. Hence you need some way of getting it out of the JVM and on to you.

If you do not log it to a file then what will you do? Files are the most reliable thing available in a JVM so you should at least put it there before sending it on the network.