max_memory_per_child reached log is ERROR level, should be INFO

[yuvalbar]

When Celery recycles a Celery worker, it emits this log:

​ERROR/ForkPoolWorker-587] child process exiting after exceeding memory limit (421812KiB / 300000KiB)

It happens in pool.py:379:

                    if used_kb > 0 and used_kb > max_memory_per_child:
                        error(MAXMEM_USED_FMT.format(
                            used_kb, max_memory_per_child))

This is not actually an error, but an expected situation where I want to recycle workers as there is no other way to reduce their memory footprint. It should probably be lowered to INFO - I'm willing to open a PR if that's acceptable. Plz let me know - Thanks!

[auvipy]

pr welcome

[truthdoug]

PR added #272

[matteius]

In my preference this would be a log.warning error. With no memory leaking and an appropriately picked value, generally this condition should not be reached so a warning level feels appropriate. I agree its not an error because its a feature of the app to restart the worker at that point.