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require 'spec_helper'
describe Gitlab::Metrics::Sampler do
let(:sampler) { described_class.new(5) }
after do
Allocations.stop if Gitlab::Metrics.mri?
end
describe '#start' do
it 'gathers a sample at a given interval' do
expect(sampler).to receive(:sleep).with(a_kind_of(Numeric))
expect(sampler).to receive(:sample)
expect(sampler).to receive(:loop).and_yield
sampler.start.join
end
end
describe '#sample' do
it 'samples various statistics' do
expect(sampler).to receive(:sample_memory_usage)
expect(sampler).to receive(:sample_file_descriptors)
expect(sampler).to receive(:sample_objects)
expect(sampler).to receive(:sample_gc)
expect(sampler).to receive(:flush)
sampler.sample
end
it 'clears any GC profiles' do
expect(sampler).to receive(:flush)
expect(GC::Profiler).to receive(:clear)
sampler.sample
end
end
describe '#flush' do
it 'schedules the metrics using Sidekiq' do
expect(Gitlab::Metrics).to receive(:submit_metrics)
.with([an_instance_of(Hash)])
sampler.sample_memory_usage
sampler.flush
end
end
describe '#sample_memory_usage' do
it 'adds a metric containing the memory usage' do
expect(Gitlab::Metrics::System).to receive(:memory_usage)
.and_return(9000)
expect(sampler).to receive(:add_metric)
.with(/memory_usage/, value: 9000)
.and_call_original
sampler.sample_memory_usage
end
end
describe '#sample_file_descriptors' do
it 'adds a metric containing the amount of open file descriptors' do
expect(Gitlab::Metrics::System).to receive(:file_descriptor_count)
.and_return(4)
expect(sampler).to receive(:add_metric)
.with(/file_descriptors/, value: 4)
.and_call_original
sampler.sample_file_descriptors
end
end
if Gitlab::Metrics.mri?
describe '#sample_objects' do
it 'adds a metric containing the amount of allocated objects' do
expect(sampler).to receive(:add_metric)
.with(/object_counts/, an_instance_of(Hash), an_instance_of(Hash))
.at_least(:once)
.and_call_original
sampler.sample_objects
end
it 'ignores classes without a name' do
expect(Allocations).to receive(:to_hash).and_return({ Class.new => 4 })
expect(sampler).not_to receive(:add_metric)
.with('object_counts', an_instance_of(Hash), type: nil)
sampler.sample_objects
end
end
end
describe '#sample_gc' do
it 'adds a metric containing garbage collection statistics' do
expect(GC::Profiler).to receive(:total_time).and_return(0.24)
expect(sampler).to receive(:add_metric)
.with(/gc_statistics/, an_instance_of(Hash))
.and_call_original
sampler.sample_gc
end
end
describe '#add_metric' do
it 'prefixes the series name for a Rails process' do
expect(sampler).to receive(:sidekiq?).and_return(false)
expect(Gitlab::Metrics::Metric).to receive(:new)
.with('rails_cats', { value: 10 }, {})
.and_call_original
sampler.add_metric('cats', value: 10)
end
it 'prefixes the series name for a Sidekiq process' do
expect(sampler).to receive(:sidekiq?).and_return(true)
expect(Gitlab::Metrics::Metric).to receive(:new)
.with('sidekiq_cats', { value: 10 }, {})
.and_call_original
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).not_to eq(last)
last = interval
end
end
end
end
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