Commit b7f49aa0 authored by Yorick Peterse's avatar Yorick Peterse

Merge branch 'configure-randomize-metrics-sample-interval' into 'master'

See merge request !2406
parents c7d9e780 057eb824
......@@ -73,6 +73,7 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
:metrics_pool_size,
:metrics_timeout,
:metrics_method_call_threshold,
:metrics_sample_interval,
:recaptcha_enabled,
:recaptcha_site_key,
:recaptcha_private_key,
......
......@@ -202,6 +202,13 @@
.help-block
A method call is only tracked when it takes longer to complete than
the given amount of milliseconds.
.form-group
= f.label :metrics_sample_interval, 'Sampler Interval (sec)', class: 'control-label col-sm-2'
.col-sm-10
= f.number_field :metrics_sample_interval, class: 'form-control'
.help-block
The sampling interval in seconds. Sampled data includes memory usage,
retained Ruby objects, file descriptors and so on.
%fieldset
%legend Spam and Anti-bot Protection
......
class AddMetricsSampleInterval < ActiveRecord::Migration
def change
add_column :application_settings, :metrics_sample_interval, :integer,
default: 15
end
end
This diff is collapsed.
......@@ -13,7 +13,8 @@ module Gitlab
timeout: current_application_settings[:metrics_timeout],
method_call_threshold: current_application_settings[:metrics_method_call_threshold],
host: current_application_settings[:metrics_host],
port: current_application_settings[:metrics_port]
port: current_application_settings[:metrics_port],
sample_interval: current_application_settings[:metrics_sample_interval] || 15
}
end
......
......@@ -7,8 +7,13 @@ module Gitlab
# statistics, etc.
class Sampler
# interval - The sampling interval in seconds.
def initialize(interval = 15)
def initialize(interval = Metrics.settings[:sample_interval])
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])
......@@ -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
......@@ -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
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