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# frozen_string_literal: true
require 'spec_helper'
RSpec.describe Gitlab::Memory::Watchdog, :aggregate_failures, :prometheus do
context 'watchdog' do
let(:logger) { instance_double(::Logger) }
let(:handler) { instance_double(described_class::NullHandler) }
let(:heap_frag_limit_gauge) { instance_double(::Prometheus::Client::Gauge) }
let(:heap_frag_violations_counter) { instance_double(::Prometheus::Client::Counter) }
let(:heap_frag_violations_handled_counter) { instance_double(::Prometheus::Client::Counter) }
let(:sleep_time) { 0.1 }
let(:max_heap_fragmentation) { 0.2 }
subject(:watchdog) do
described_class.new(handler: handler, logger: logger, sleep_time_seconds: sleep_time,
max_strikes: max_strikes, max_heap_fragmentation: max_heap_fragmentation)
end
before do
allow(handler).to receive(:on_high_heap_fragmentation).and_return(true)
allow(logger).to receive(:warn)
allow(logger).to receive(:info)
allow(Gitlab::Metrics::Memory).to receive(:gc_heap_fragmentation).and_return(fragmentation)
end
after do
watchdog.stop
end
context 'when starting up' do
let(:fragmentation) { 0 }
let(:max_strikes) { 0 }
it 'sets the heap fragmentation limit gauge' do
allow(Gitlab::Metrics).to receive(:gauge).and_return(heap_frag_limit_gauge)
expect(heap_frag_limit_gauge).to receive(:set).with({}, max_heap_fragmentation)
end
context 'when no settings are set in the environment' do
it 'initializes with defaults' do
watchdog = described_class.new(handler: handler, logger: logger)
expect(watchdog.max_heap_fragmentation).to eq(described_class::DEFAULT_HEAP_FRAG_THRESHOLD)
expect(watchdog.max_strikes).to eq(described_class::DEFAULT_MAX_STRIKES)
expect(watchdog.sleep_time_seconds).to eq(described_class::DEFAULT_SLEEP_TIME_SECONDS)
end
end
context 'when settings are passed through the environment' do
before do
stub_env('GITLAB_MEMWD_MAX_HEAP_FRAG', 1)
stub_env('GITLAB_MEMWD_MAX_STRIKES', 2)
stub_env('GITLAB_MEMWD_SLEEP_TIME_SEC', 3)
end
it 'initializes with these settings' do
watchdog = described_class.new(handler: handler, logger: logger)
expect(watchdog.max_heap_fragmentation).to eq(1)
expect(watchdog.max_strikes).to eq(2)
expect(watchdog.sleep_time_seconds).to eq(3)
end
end
end
context 'when process does not exceed heap fragmentation threshold' do
let(:fragmentation) { max_heap_fragmentation - 0.1 }
let(:max_strikes) { 0 } # To rule out that we were granting too many strikes.
it 'does not signal the handler' do
expect(handler).not_to receive(:on_high_heap_fragmentation)
watchdog.start
sleep sleep_time * 3
end
end
context 'when process exceeds heap fragmentation threshold permanently' do
let(:fragmentation) { max_heap_fragmentation + 0.1 }
before do
allow(Gitlab::Metrics).to receive(:counter)
.with(:gitlab_memwd_heap_frag_violations_total, anything, anything)
.and_return(heap_frag_violations_counter)
allow(Gitlab::Metrics).to receive(:counter)
.with(:gitlab_memwd_heap_frag_violations_handled_total, anything, anything)
.and_return(heap_frag_violations_handled_counter)
allow(heap_frag_violations_counter).to receive(:increment)
allow(heap_frag_violations_handled_counter).to receive(:increment)
end
context 'when process has not exceeded allowed number of strikes' do
let(:max_strikes) { 10 }
it 'does not signal the handler' do
expect(handler).not_to receive(:on_high_heap_fragmentation)
watchdog.start
sleep sleep_time * 3
end
it 'does not log any events' do
expect(logger).not_to receive(:warn)
watchdog.start
sleep sleep_time * 3
end
it 'increments the violations counter' do
expect(heap_frag_violations_counter).to receive(:increment)
watchdog.start
sleep sleep_time * 3
end
it 'does not increment violations handled counter' do
expect(heap_frag_violations_handled_counter).not_to receive(:increment)
watchdog.start
sleep sleep_time * 3
end
end
context 'when process exceeds the allowed number of strikes' do
let(:max_strikes) { 1 }
it 'signals the handler and resets strike counter' do
expect(handler).to receive(:on_high_heap_fragmentation).and_return(true)
watchdog.start
sleep sleep_time * 3
expect(watchdog.strikes).to eq(0)
end
it 'logs the event' do
expect(::Prometheus::PidProvider).to receive(:worker_id).at_least(:once).and_return('worker_1')
expect(Gitlab::Metrics::System).to receive(:memory_usage_rss).at_least(:once).and_return(1024)
expect(logger).to receive(:warn).with({
message: 'heap fragmentation limit exceeded',
pid: Process.pid,
worker_id: 'worker_1',
memwd_handler_class: 'RSpec::Mocks::InstanceVerifyingDouble',
memwd_sleep_time_s: sleep_time,
memwd_max_heap_frag: max_heap_fragmentation,
memwd_cur_heap_frag: fragmentation,
memwd_max_strikes: max_strikes,
memwd_cur_strikes: max_strikes + 1,
memwd_rss_bytes: 1024
})
watchdog.start
sleep sleep_time * 3
end
it 'increments both the violations and violations handled counters' do
expect(heap_frag_violations_counter).to receive(:increment)
expect(heap_frag_violations_handled_counter).to receive(:increment)
watchdog.start
sleep sleep_time * 3
end
context 'when enforce_memory_watchdog ops toggle is off' do
before do
stub_feature_flags(enforce_memory_watchdog: false)
end
it 'always uses the NullHandler' do
expect(handler).not_to receive(:on_high_heap_fragmentation)
expect(described_class::NullHandler.instance).to(
receive(:on_high_heap_fragmentation).with(fragmentation).and_return(true)
)
watchdog.start
sleep sleep_time * 3
end
end
end
context 'when handler result is true' do
let(:max_strikes) { 1 }
it 'considers the event handled and stops itself' do
expect(handler).to receive(:on_high_heap_fragmentation).once.and_return(true)
watchdog.start
sleep sleep_time * 3
end
end
context 'when handler result is false' do
let(:max_strikes) { 1 }
it 'keeps running' do
# Return true the third time to terminate the daemon.
expect(handler).to receive(:on_high_heap_fragmentation).and_return(false, false, true)
watchdog.start
sleep sleep_time * 4
end
end
end
context 'when process exceeds heap fragmentation threshold temporarily' do
let(:fragmentation) { max_heap_fragmentation }
let(:max_strikes) { 1 }
before do
allow(Gitlab::Metrics::Memory).to receive(:gc_heap_fragmentation).and_return(
fragmentation - 0.1,
fragmentation + 0.2,
fragmentation - 0.1,
fragmentation + 0.1
)
end
it 'does not signal the handler' do
expect(handler).not_to receive(:on_high_heap_fragmentation)
watchdog.start
sleep sleep_time * 4
end
end
context 'when gitlab_memory_watchdog ops toggle is off' do
let(:fragmentation) { 0 }
let(:max_strikes) { 0 }
before do
stub_feature_flags(gitlab_memory_watchdog: false)
end
it 'does not monitor heap fragmentation' do
expect(Gitlab::Metrics::Memory).not_to receive(:gc_heap_fragmentation)
watchdog.start
sleep sleep_time * 3
end
end
end
context 'handlers' do
context 'NullHandler' do
subject(:handler) { described_class::NullHandler.instance }
describe '#on_high_heap_fragmentation' do
it 'does nothing' do
expect(handler.on_high_heap_fragmentation(1.0)).to be(false)
end
end
end
context 'TermProcessHandler' do
subject(:handler) { described_class::TermProcessHandler.new(42) }
describe '#on_high_heap_fragmentation' do
it 'sends SIGTERM to the current process' do
expect(Process).to receive(:kill).with(:TERM, 42)
expect(handler.on_high_heap_fragmentation(1.0)).to be(true)
end
end
end
context 'PumaHandler' do
# rubocop: disable RSpec/VerifiedDoubles
# In tests, the Puma constant is not loaded so we cannot make this an instance_double.
let(:puma_worker_handle_class) { double('Puma::Cluster::WorkerHandle') }
let(:puma_worker_handle) { double('worker') }
# rubocop: enable RSpec/VerifiedDoubles
subject(:handler) { described_class::PumaHandler.new({}) }
before do
stub_const('::Puma::Cluster::WorkerHandle', puma_worker_handle_class)
end
describe '#on_high_heap_fragmentation' do
it 'invokes orderly termination via Puma API' do
expect(puma_worker_handle_class).to receive(:new).and_return(puma_worker_handle)
expect(puma_worker_handle).to receive(:term)
expect(handler.on_high_heap_fragmentation(1.0)).to be(true)
end
end
end
end
end
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