Commit 905f8d76 authored by Yorick Peterse's avatar Yorick Peterse

Reduce instrumentation overhead

This reduces the overhead of the method instrumentation code primarily
by reducing the number of method calls. There are also some other small
optimisations such as not casting timing values to Floats (there's no
particular need for this), using Symbols for method call metric names,
and reducing the number of Hash lookups for instrumented methods.

The exact impact depends on the code being executed. For example, for a
method that's only called once the difference won't be very noticeable.
However, for methods that are called many times the difference can be
more significant.

For example, the loading time of a large commit
(nrclark/dummy_project@81ebdea5df2fb42e59257cb3eaad671a5c53ca36)
was reduced from around 19 seconds to around 15 seconds using these
changes.
parent 17be364d
......@@ -15,6 +15,7 @@ v 8.11.0 (unreleased)
- Add build event color in HipChat messages (David Eisner)
- Make fork counter always clickable. !5463 (winniehell)
- All created issues, API or WebUI, can be submitted to Akismet for spam check !5333
- The overhead of instrumented method calls has been reduced
- Remove `search_id` of labels dropdown filter to fix 'Missleading URI for labels in Merge Requests and Issues view'. !5368 (Scott Le)
- Load project invited groups and members eagerly in `ProjectTeam#fetch_members`
- Make branches sortable without push permission !5462 (winniehell)
......
......@@ -124,6 +124,11 @@ module Gitlab
trans.action = action if trans
end
# Returns the prefix to use for the name of a series.
def self.series_prefix
@series_prefix ||= Sidekiq.server? ? 'sidekiq_' : 'rails_'
end
# When enabled this should be set before being used as the usual pattern
# "@foo ||= bar" is _not_ thread-safe.
if enabled?
......
......@@ -9,14 +9,17 @@ module Gitlab
#
# Gitlab::Metrics::Instrumentation.instrument_method(User, :by_login)
module Instrumentation
SERIES = 'method_calls'
PROXY_IVAR = :@__gitlab_instrumentation_proxy
def self.configure
yield self
end
# Returns the name of the series to use for storing method calls.
def self.series
@series ||= "#{Metrics.series_prefix}method_calls"
end
# Instruments a class method.
#
# mod - The module to instrument as a Module/Class.
......@@ -141,15 +144,15 @@ module Gitlab
# generated method _only_ accepts regular arguments if the underlying
# method also accepts them.
if method.arity == 0
args_signature = '&block'
args_signature = ''
else
args_signature = '*args, &block'
args_signature = '*args'
end
proxy_module.class_eval <<-EOF, __FILE__, __LINE__ + 1
def #{name}(#{args_signature})
if trans = Gitlab::Metrics::Instrumentation.transaction
trans.measure_method(#{label.inspect}) { super }
trans.method_call_for(#{label.to_sym.inspect}).measure { super }
else
super
end
......
......@@ -11,8 +11,8 @@ module Gitlab
def initialize(name, series)
@name = name
@series = series
@real_time = 0.0
@cpu_time = 0.0
@real_time = 0
@cpu_time = 0
@call_count = 0
end
......
......@@ -35,12 +35,12 @@ module Gitlab
if Process.const_defined?(:CLOCK_THREAD_CPUTIME_ID)
def self.cpu_time
Process.
clock_gettime(Process::CLOCK_THREAD_CPUTIME_ID, :millisecond).to_f
clock_gettime(Process::CLOCK_THREAD_CPUTIME_ID, :millisecond)
end
else
def self.cpu_time
Process.
clock_gettime(Process::CLOCK_PROCESS_CPUTIME_ID, :millisecond).to_f
clock_gettime(Process::CLOCK_PROCESS_CPUTIME_ID, :millisecond)
end
end
......@@ -48,14 +48,14 @@ module Gitlab
#
# Returns the time as a Float.
def self.real_time(precision = :millisecond)
Process.clock_gettime(Process::CLOCK_REALTIME, precision).to_f
Process.clock_gettime(Process::CLOCK_REALTIME, precision)
end
# Returns the current monotonic clock time in a given precision.
#
# Returns the time as a Float.
def self.monotonic_time(precision = :millisecond)
Process.clock_gettime(Process::CLOCK_MONOTONIC, precision).to_f
Process.clock_gettime(Process::CLOCK_MONOTONIC, precision)
end
end
end
......
......@@ -52,23 +52,16 @@ module Gitlab
end
def add_metric(series, values, tags = {})
@metrics << Metric.new("#{series_prefix}#{series}", values, tags)
@metrics << Metric.new("#{Metrics.series_prefix}#{series}", values, tags)
end
# Measures the time it takes to execute a method.
#
# Multiple calls to the same method add up to the total runtime of the
# method.
#
# name - The full name of the method to measure (e.g. `User#sign_in`).
def measure_method(name, &block)
unless @methods[name]
series = "#{series_prefix}#{Instrumentation::SERIES}"
@methods[name] = MethodCall.new(name, series)
# Returns a MethodCall object for the given name.
def method_call_for(name)
unless method = @methods[name]
@methods[name] = method = MethodCall.new(name, Instrumentation.series)
end
@methods[name].measure(&block)
method
end
def increment(name, value)
......@@ -115,14 +108,6 @@ module Gitlab
Metrics.submit_metrics(submit_hashes)
end
def sidekiq?
Sidekiq.server?
end
def series_prefix
sidekiq? ? 'sidekiq_' : 'rails_'
end
end
end
end
......@@ -39,6 +39,12 @@ describe Gitlab::Metrics::Instrumentation do
allow(@dummy).to receive(:name).and_return('Dummy')
end
describe '.series' do
it 'returns a String' do
expect(described_class.series).to be_an_instance_of(String)
end
end
describe '.configure' do
it 'yields self' do
described_class.configure do |c|
......@@ -78,8 +84,7 @@ describe Gitlab::Metrics::Instrumentation do
allow(described_class).to receive(:transaction).
and_return(transaction)
expect(transaction).to receive(:measure_method).
with('Dummy.foo')
expect_any_instance_of(Gitlab::Metrics::MethodCall).to receive(:measure)
@dummy.foo
end
......@@ -157,8 +162,7 @@ describe Gitlab::Metrics::Instrumentation do
allow(described_class).to receive(:transaction).
and_return(transaction)
expect(transaction).to receive(:measure_method).
with('Dummy#bar')
expect_any_instance_of(Gitlab::Metrics::MethodCall).to receive(:measure)
@dummy.new.bar
end
......
......@@ -28,20 +28,20 @@ describe Gitlab::Metrics::System do
end
describe '.cpu_time' do
it 'returns a Float' do
expect(described_class.cpu_time).to be_an_instance_of(Float)
it 'returns a Fixnum' do
expect(described_class.cpu_time).to be_an_instance_of(Fixnum)
end
end
describe '.real_time' do
it 'returns a Float' do
expect(described_class.real_time).to be_an_instance_of(Float)
it 'returns a Fixnum' do
expect(described_class.real_time).to be_an_instance_of(Fixnum)
end
end
describe '.monotonic_time' do
it 'returns a Float' do
expect(described_class.monotonic_time).to be_an_instance_of(Float)
it 'returns a Fixnum' do
expect(described_class.monotonic_time).to be_an_instance_of(Fixnum)
end
end
end
......@@ -46,19 +46,11 @@ describe Gitlab::Metrics::Transaction do
end
end
describe '#measure_method' do
it 'adds a new method if it does not exist already' do
transaction.measure_method('Foo#bar') { 'foo' }
describe '#method_call_for' do
it 'returns a MethodCall' do
method = transaction.method_call_for('Foo#bar')
expect(transaction.methods['Foo#bar']).
to be_an_instance_of(Gitlab::Metrics::MethodCall)
end
it 'adds timings to an existing method call' do
transaction.measure_method('Foo#bar') { 'foo' }
transaction.measure_method('Foo#bar') { 'foo' }
expect(transaction.methods['Foo#bar'].call_count).to eq(2)
expect(method).to be_an_instance_of(Gitlab::Metrics::MethodCall)
end
end
......
......@@ -147,4 +147,10 @@ describe Gitlab::Metrics do
end
end
end
describe '#series_prefix' do
it 'returns a String' do
expect(described_class.series_prefix).to be_an_instance_of(String)
end
end
end
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