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> LOG005 use exception() within an exception handler In Python, exception handling is part of the normal control flow. Therefore, when an exception happens, i

by teddyh 3y ago

> LOG005 use exception() within an exception handler In Python, exception handling is part of the normal control flow. Therefore, when an exception happens, it is not always the case that you want to log a full stack trace. try: thing = things[0] except IndexError: log.error("Not enough things!") return I think that even recommending a log.exception() here would actually be a bad thing.

deleted 3y ago
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kamikaz1k 3y ago
If it’s expected control flow, would you log it? If it’s expected, I tend not to log it.
- msm_ 3y ago
  It depends on the situation. There are cases when I "expect the exception" - for example anything that touches the network has a tiny chance of failing. I want to know how often this happen, because too many network errors probably means that something is down and needs to be investigated (and we have alerts for this, based on logs). But to be fair I usually just log .exception() in this case anyway (even if I know exactly what the exception will be).
- teddyh 3y ago
  Oh no, I would not necessarily log an exception, the same way I don’t log every time an ”else” clause is reached. But in the places I do want to log.error("something") in an exception handler, I don’t want some linter complaining that since there is an active exception, it thinks I ought to have used log.exception().
- globular-toast 3y ago
  Depends what you're logging. An info level log is quite explicitly for an expected path, e.g. "config not found, using defaults". This rule is only for error calls, though. In that case, yeah, you wouldn't log an error for an expected path.
bobbyi 3y ago
log.exception is also usually bad when you are re-raising the exception. That often results in same stacktrace logged multiple times in a row which can be confusing or at least annoyingly verbose. But it can be helpful to log an error message (without stacktrace) to give context that is available only in this frame before letting the exception propagate to whoever ultimately handles and logs it.
globular-toast 3y ago
Why would you log an error for an expected path? That should just be an info or debug level log, not error. In any case, it's really easy to disable errors either by line, module or project if really necessary.
- teddyh 3y ago
  If you had said log.critical(), I might (might) have agreed with you. But a log.error() is not necessarily an error on the Python level, and should not necessarily spam a backtrace into the log.

by teddyh 3y ago

deleted 3y ago

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kamikaz1k 3y ago

If it’s expected control flow, would you log it? If it’s expected, I tend not to log it.

msm_ 3y ago
It depends on the situation. There are cases when I "expect the exception" - for example anything that touches the network has a tiny chance of failing. I want to know how often this happen, because too many network errors probably means that something is down and needs to be investigated (and we have alerts for this, based on logs). But to be fair I usually just log .exception() in this case anyway (even if I know exactly what the exception will be).
teddyh 3y ago
Oh no, I would not necessarily log an exception, the same way I don’t log every time an ”else” clause is reached. But in the places I do want to log.error("something") in an exception handler, I don’t want some linter complaining that since there is an active exception, it thinks I ought to have used log.exception().
globular-toast 3y ago
Depends what you're logging. An info level log is quite explicitly for an expected path, e.g. "config not found, using defaults". This rule is only for error calls, though. In that case, yeah, you wouldn't log an error for an expected path.

bobbyi 3y ago

log.exception is also usually bad when you are re-raising the exception. That often results in same stacktrace logged multiple times in a row which can be confusing or at least annoyingly verbose. But it can be helpful to log an error message (without stacktrace) to give context that is available only in this frame before letting the exception propagate to whoever ultimately handles and logs it.

globular-toast 3y ago

Why would you log an error for an expected path? That should just be an info or debug level log, not error. In any case, it's really easy to disable errors either by line, module or project if really necessary.

teddyh 3y ago
If you had said log.critical(), I might (might) have agreed with you. But a log.error() is not necessarily an error on the Python level, and should not necessarily spam a backtrace into the log.