ArithmeticError: bad argument in arithmetic expression

[tomtaylor]

Describe the bug

We see occasional alerts with the following stack trace:

ArithmeticError: bad argument in arithmetic expression
  Module "erlang", in :erlang.*/2
  File "lib/new_relic/harvest/collector/metric/harvester.ex", line 158, in NewRelic.Harvest.Collector.Metric.Harvester.merge_metric/2
  File "lib/enum.ex", line 2546, in Enum."-reduce/3-lists^foldl/2-0-"/3
  File "lib/new_relic/harvest/collector/metric/harvester.ex", line 49, in NewRelic.Harvest.Collector.Metric.Harvester.handle_cast/2
  File "gen_server.erl", line 2371, in :gen_server.try_handle_cast/3
  File "gen_server.erl", line 2433, in :gen_server.handle_msg/6
  File "proc_lib.erl", line 329, in :proc_lib.init_p_do_apply/3

In this case, the arguments were {:error, :timeout} and 10000.

This has happened 12 times in the last 90 days.

Environment

• Elixir & Erlang version (elixir -v): 1.18.2
• Agent version (mix deps | grep new_relic_agent): 1.34.0

[binaryseed]

Are you reporting any custom metrics in your application? Somehow an error tuple is being passed in as the value for a metric.

We could put a guard on the API function to make sure it's passed a number

[bagnaram]

We also experience this issue with the cpu_utilization metric. Perhaps it is timing out and returning the error tuple. The error isn't handled here and is lost in the stack trace