The `not` operator in Elixir only works with booleans, not nil values.
When Exq process doesn't exist, Process.whereis(Exq) returns nil, causing
`:badarg` error when used with `not`.
Error:
Class=:error
Reason=:badarg
{:erlang, :not, [nil], [error_info: %{module: :erl_erts_errors}]}
Changed from:
not Process.whereis(Exq)
To:
is_nil(Process.whereis(Exq))
This properly checks if the process exists without causing runtime errors.
- Check if Exq process is running before attempting to collect metrics
- Change rescue to catch to handle process exits (:noproc)
- Prevents error logs in environments where Exq is not configured
Added telemetry metrics for monitoring:
Exq Metrics:
- Queue sizes for all queues (default, discovery, polling, monitoring, maintenance)
- Number of busy worker processes
- Total number of worker processes
Redis/Valkey Metrics:
- Connected clients
- Memory usage
- Total commands processed
Metrics are collected every 10 seconds via telemetry_poller and displayed
in LiveDashboard at /dashboard
