diff options
| -rw-r--r-- | lib/gitlab/metrics/sampler.rb | 28 | ||||
| -rw-r--r-- | spec/lib/gitlab/metrics/sampler_spec.rb | 22 |
2 files changed, 46 insertions, 4 deletions
diff --git a/lib/gitlab/metrics/sampler.rb b/lib/gitlab/metrics/sampler.rb index c2913841de3..fc709222a9b 100644 --- a/lib/gitlab/metrics/sampler.rb +++ b/lib/gitlab/metrics/sampler.rb @@ -8,8 +8,13 @@ module Gitlab class Sampler # interval - The sampling interval in seconds. def initialize(interval = Metrics.settings[:sample_interval]) - @interval = interval - @metrics = [] + interval_half = interval.to_f / 2 + + @interval = interval + @interval_steps = (-interval_half..interval_half).step(0.1).to_a + @last_step = nil + + @metrics = [] @last_minor_gc = Delta.new(GC.stat[:minor_gc_count]) @last_major_gc = Delta.new(GC.stat[:major_gc_count]) @@ -26,7 +31,7 @@ module Gitlab Thread.current.abort_on_exception = true loop do - sleep(@interval) + sleep(sleep_interval) sample end @@ -102,6 +107,23 @@ module Gitlab def sidekiq? Sidekiq.server? end + + # Returns the sleep interval with a random adjustment. + # + # The random adjustment is put in place to ensure we: + # + # 1. Don't generate samples at the exact same interval every time (thus + # potentially missing anything that happens in between samples). + # 2. Don't sample data at the same interval two times in a row. + def sleep_interval + while step = @interval_steps.sample + if step != @last_step + @last_step = step + + return @interval + @last_step + end + end + end end end end diff --git a/spec/lib/gitlab/metrics/sampler_spec.rb b/spec/lib/gitlab/metrics/sampler_spec.rb index 27211350fbe..38da77adc9f 100644 --- a/spec/lib/gitlab/metrics/sampler_spec.rb +++ b/spec/lib/gitlab/metrics/sampler_spec.rb @@ -9,7 +9,7 @@ describe Gitlab::Metrics::Sampler do describe '#start' do it 'gathers a sample at a given interval' do - expect(sampler).to receive(:sleep).with(5) + expect(sampler).to receive(:sleep).with(a_kind_of(Numeric)) expect(sampler).to receive(:sample) expect(sampler).to receive(:loop).and_yield @@ -116,4 +116,24 @@ describe Gitlab::Metrics::Sampler do sampler.add_metric('cats', value: 10) end end + + describe '#sleep_interval' do + it 'returns a Numeric' do + expect(sampler.sleep_interval).to be_a_kind_of(Numeric) + end + + # Testing random behaviour is very hard, so treat this test as a basic smoke + # test instead of a very accurate behaviour/unit test. + it 'does not return the same interval twice in a row' do + last = nil + + 100.times do + interval = sampler.sleep_interval + + expect(interval).to_not eq(last) + + last = interval + end + end + end end |