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vmstats is a tiny Erlang app that gathers metrics on the Erlang VM and sends them to a configurable sink (e.g., StatsD).


The different metrics that vmstats gathers include:

  • the error_logger queue length
  • the number of modules loaded
  • the number of processes
  • the process limit
  • the length of the run queue
  • the scheduler usage as a percentage (disabled by default)
  • memory used for ETS tables, atoms, processes, binaries and the total memory
  • garbage collection count per interval
  • words reclaimed in garbage collections per interval
  • reduction increment count per interval
  • IO data (bytes in and out) per interval
  • global amount of messages in queues on a node
  • the VM uptime


vmstats can be built using rebar3:

$ rebar3 compile

Once you have vmstats set up, just add it to the list of applications to start in order to start gathering data. You'll need a sink (a module that implements the vmstats_sink behaviour) to send metrics to.


The following is a list of the possible options for the configuration of the vmstats app:

  • sink - (module) a module that implements the vmstats_sink behaviour; vmstats metrics will be collected through this module.
  • base_key - (string) every metric name is prepended with this base key. Defaults to "vmstats".
  • key_separator - (char) used as a separator between the parts of metric keys. Defaults to $..
  • interval - (integer) the time (in milliseconds) between metric gatherings. Defaults to 1000 (1s).
  • sched_time - (boolean) whether to gather statistics about scheduler wall time. Defaults to true.
  • memory_metrics - (proplist of metric and key) what fields to collect statistics for. Available fields can be found here. Default list is [{total, total}, {processes_used, procs_used}, {atom_used, atom_used}, {binary, binary}, {ets, ets}].

vmstats_sink behaviour

vmstats sinks must implement the vmstats_sink behaviour. This behaviour only specifies one function:

-callback collect(Type :: counter | gauge | timing,
                  Key :: iodata(),
                  Value :: term()) -> ok.

I was basing myself on 'master' and stuff started breaking!

That's because you should use tags for stable versions instead! The changelog should let you know what to expect.


Make changes and be sure to test them ($ rebar3 eunit).


See the file.


See the license file.


tiny Erlang app to generate information on the Erlang VM



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