In java streams using .peek() is regarded as to be used for debugging purposes only, would logging be considered as debugging?

The documentation of peek describes the intent as

This method exists mainly to support debugging, where you want to see the elements as they flow past a certain point in a pipeline.

An expression of the form .peek(classInSchool -> log.debug("Processing classroom {} in sixth grade without classroom.", classInSchool) fulfills this intend, as it is about reporting the processing of an element. It doesn’t matter whether you use the logging framework or just print statements, as in the documentation’s example, .peek(e -> System.out.println("Filtered value: " + e)). In either case, the intent matters, not the technical approach. If someone used peek with the intent to print all elements, it would be wrong, even if it used the same technical approach as the documentation’s example (System.out.println).

The documentation doesn’t mandate that you have to distinguish between production environment or debugging environment, to remove the peek usage for the former. Actually, your use would even fulfill that, as the logging framework allows you to mute that action via the configurable logging level.

I would still suggest to keep in mind that for some pipelines, inserting a peek operation may insert more overhead than the actual operation (or hinder the JVM’s loop optimizations to such degree). But if you do not experience performance problems, you may follow the old advice to not try to optimize unless you have a real reason…

Peek should be avoided as for certain terminal operations it may not be called, see this answer. In that example it would probably be better to do the logging inside the action of forEach rather than using peek. Debugging in this situation means temporary code used for fixing a bug or diagnosing an issue.