Exception logged

[xuyf1001]

Describe the bug

my rabbitmq is v3.8.27，on k8s，I hava enabled rabbitmq_management，After using the plug-in for a period of time, the following error is reported:
2023-12-26 07:29:14.348 [error] <0.29224.51> Ranch listener {acceptor,{0,0,0,0,0,0,0,0},9090}, connection process <0.29224.51>, stream 661 had its request process <0.4120.52> exit with reason badarith and stacktrace [{erlang,'+',[undefined,2071],[{error_info,#{module => erl_erts_errors}}]},{prometheus_mnesia_collector,'-get_memory_usage/0-fun-0-',2,[{file,"src/collectors/mnesia/prometheus_mnesia_collector.erl"},{line,199}]},{lists,foldl,3,[{file,"lists.erl"},{line,1267}]},{prometheus_mnesia_collector,get_memory_usage,0,[{file,"src/collectors/mnesia/prometheus_mnesia_collector.erl"},{line,201}]},{prometheus_mnesia_collector,metrics,1,[{file,"src/collectors/mnesia/prometheus_mnesia_collector.erl"},{line,124}]},{prometheus_mnesia_collector,collect_mf,2,[{file,"src/collectors/mnesia/prometheus_mnesia_collector.erl"},{line,108}]},{prometheus_collector,collect_mf,3,[{file,"src/prometheus_collector.erl"},{line,156}]},{prometheus_registry,'-collect/2-lc$^0/1-0-',3,[{file,"src/prometheus_registry.erl"},{line,86}]}]

Ours is a 3-node cluster, and the monitoring plug-in of two nodes reported this error, I don't know what the cause is, can you help solve it?

Reproduction steps

1.rabbitmqctl set_policy -p zat ha-allqueue "^" '{"ha-mode":"all"}'
2.Write business data

Expected behavior

Hope to know if this is a hidden bug of the monitoring plugin

Additional context

no

[michaelklishin]

The exception comes from prometheus_mnesia_collector:get_memory_usage/0, a part of the Prometheus plugin.

One of the values collected by the plugin from the schema database was undefined. We don't have any context to draw conclusions from but most likely the plugin tried to collect metrics while some tables were still syncing from a peer node.

FYI, classic mirrored queues are deprecated and will be removed from RabbitMQ in early 2024.

Specifically "ha-mode": "all" has been recommended against for years.

[michaelklishin]

Also, RabbitMQ 3.8 has reached EOL in 2022. In fact, 3.10 is about to reach EOL on Dec 31st.