diff options
| -rw-r--r-- | lib/gitlab/metrics/metric.rb | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/lib/gitlab/metrics/metric.rb b/lib/gitlab/metrics/metric.rb index 7ea9555cc8c..1cd1ca30f70 100644 --- a/lib/gitlab/metrics/metric.rb +++ b/lib/gitlab/metrics/metric.rb @@ -2,6 +2,8 @@ module Gitlab module Metrics # Class for storing details of a single metric (label, value, etc). class Metric + JITTER_RANGE = 0.000001..0.001 + attr_reader :series, :values, :tags, :created_at # series - The name of the series (as a String) to store the metric in. @@ -16,11 +18,29 @@ module Gitlab # Returns a Hash in a format that can be directly written to InfluxDB. def to_hash + # InfluxDB overwrites an existing point if a new point has the same + # series, tag set, and timestamp. In a highly concurrent environment + # this means that using the number of seconds since the Unix epoch is + # inevitably going to collide with another timestamp. For example, two + # Rails requests processed by different processes may end up generating + # metrics using the _exact_ same timestamp (in seconds). + # + # Due to the way InfluxDB is set up there's no solution to this problem, + # all we can do is lower the amount of collisions. We do this by using + # Time#to_f which returns the seconds as a Float providing greater + # accuracy. We then add a small random value that is large enough to + # distinguish most timestamps but small enough to not alter the amount + # of seconds. + # + # See https://gitlab.com/gitlab-com/operations/issues/175 for more + # information. + time = @created_at.to_f + rand(JITTER_RANGE) + { series: @series, tags: @tags, values: @values, - timestamp: @created_at.to_i * 1_000_000_000 + timestamp: (time * 1_000_000_000).to_i } end end |