The code that computes data for and assembles your log message may end up executing logic that affects the system elsewhere. If you put that code under conditional, your program will behave differently depending on the logging configuration; if you put it outside, you end up wasting potentially substantial amount of work building log messages that never get used.
As I said, responding to another comment of yours, a distributed system I worked on produced a few GB a day. The logs were rotated daily. They were never transmitted anywhere, during normal operation. When things go wrong, sure, we look at them, and generate even more logging. But that was rare. I cannot stress enough how much of a non-issue log volume was in practice.
So I ask you to quantify: What counts (to you) as voluminous, as in daily log file sizes, and how many times they are sent over the network?
I mean "a lot" or more specifically; "a whole lot."
Here is an exercise which illustrates this. For the purposes here, assume ASCII characters are used for log entries to make the math a bit easier.
Suppose the following:
Each log statement is 100 characters.
Each service invocation emits 50 log statements.
Average transactions per second during high usage is 200tps.
High usage is on average 2 hours per day.
100 x 50 x 200 x 60 x 60 x 2 = 7_200_000_000 = 7.2GB / day
The quantification is above and regarding log entries being sent over a network - in many production systems, log entries are unconditionally sent to a log aggregator and never stored in a local file system.
But in normal usage, even in the scenario you describe your argument about log volume is not convincing.
Resorting to an ad hominem and non sequiturs are we? Really?
C'mon, you are better than that.
I assumed nothing of the sort. What I did was identify an anti-pattern and describe an alternative which experience has shown to be a better approach.
"Incompetence" is your word, not mine.
> ... and adding the label of "anti-pattern" to something that's evidently got so much nuance to it.
I fail to see the nuance you apparently can see.
>> the non-trivial cost implications of voluminous log output
> If log output is conditional at compile time there are no non-trivial cost implications, and even at runtime the costs are often trivial.
Cloud deployment requires transmission of log entries to one or more log aggregators in order to be known.
By definition, this involves network I/O.
Network communication is orders of magnitude slower than local I/O.
Useless logging of "function entry/exit, with param values" increases pressure on network I/O.
Unless logging is allowed to be lossy, which it never is, transmission must be completed when log buffers are near full capacity.
Provisioning production systems having excessive logging can often require more resources than those which do not excessively log.
Thus disproving:
> ... even at runtime the costs are often trivial.
When considering the implication of voluminous log output in a production environment.