Statistics

This page is about the statistics support for Dovecot:

New in version v2.3.

For v2.1 and v2.2 see Old Statistics.

See Events for list of all events that can be used in statistics.

Dovecot supports gathering statistics from “Events Design”. Eventually all of the log messages should be events, so it will be possible to configure Dovecot to get statistics for anything that is logged. For debug messages it’s possible to get statistics even if the message itself isn’t logged.

Currently there are no statistics logged by default (but this might change). You’ll need to add some metrics:

metric name {
  # Individual events can be identified either by their name or source file:line location.
  # The source location of course can change between Dovecot versions, so it should be
  # avoided.
  event_name = example_event_name
  #source_location = example.c:123

  # Space-separated list of categories that must match the event (e.g. "mail" or "storage")
  #categories =

  # List of fields in event parameters that are included in the metrics.
  # All events have a default "duration" field that doesn't need to be listed here.
  #fields =

  # List of key=value pairs that must match the event. The value can contain '?' and '*' wildcards.
  #filter {
  #  field_key = wildcard
  #}
}

Listing Statistics

The gathered statistics are available by running:

doveadm stats dump

Each event has a duration field, which tracks in microseconds how long the event existed. For example with imap_command_finished field it could be:

metric_name          field      count  sum       min  max     avg      median stddev %95
imap_commands        duration   35     1190122   162  340477  34003    244    31215  188637

The above means:

count There have been 35 IMAP commands
sum The IMAP commands were running in total for 1190122 microseconds (= 1.1 seconds)
min The fastest IMAP command took 162 microseconds
max The slowest IMAP command took 340477 microseconds
avg The average time spent on an IMAP commands was 34003 microseconds
median The median time spent on an IMAP command was 244 microseconds
stddev Standard deviation for the time spent on IMAP commands
%95 95% of the IMAP commands took 188637 microseconds or less

The other fields (than duration) track whatever that field represents. For example with imap_command_finished’s bytes_in field could be tracking how many bytes were being used by the IMAP commands. Non-numeric fields can also be tracked, although only the count is relevant to those.

The list of fields can be specified with the -f parameter. The default is:

doveadm stats dump -f 'count sum min max avg median stddev %95'

It’s also possible to specify other percentiles than just 95%, for example:

doveadm stats dump -f 'count sum min max avg median stddev %95 %99 %99.9 %99.99'

The stats counters are reset whenever the stats process is started, which also means a dovecot reload will reset statistics. Using doveadm stats -r parameter will also reset the statistics atomically after they’re dumped.

Examples:

metric imap_select_no {
  event_name = imap_command_finished
  filter {
    name = SELECT
    tagged_reply_state = NO
  }
}

metric imap_select_no_notfound {
  event_name = imap_command_finished
  filter {
    name = SELECT
    tagged_reply = NO*Mailbox doesn't exist:*
  }
}

metric storage_http_gets {
  event_name = http_request_finished
  categories = storage
  filter {
    method = get
  }
}