140 lines
4.8 KiB
Ruby
140 lines
4.8 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
# trigger stackprof by sending a SIGUSR2 signal
|
|
#
|
|
# Docs: https://docs.gitlab.com/ee/development/performance.html#production
|
|
|
|
module Gitlab
|
|
class StackProf
|
|
DEFAULT_FILE_PREFIX = Dir.tmpdir
|
|
DEFAULT_TIMEOUT_SEC = 30
|
|
DEFAULT_MODE = :cpu
|
|
# Sample interval as a frequency in microseconds (~99hz); appropriate for CPU profiles
|
|
DEFAULT_INTERVAL_US = 10_100
|
|
# Sample interval in event occurrences (n = every nth event); appropriate for allocation profiles
|
|
DEFAULT_INTERVAL_EVENTS = 100
|
|
|
|
# this is a workaround for sidekiq, which defines its own SIGUSR2 handler.
|
|
# by defering to the sidekiq startup event, we get to set up our own
|
|
# handler late enough.
|
|
# see also: https://github.com/mperham/sidekiq/pull/4653
|
|
def self.install
|
|
require 'stackprof'
|
|
require 'tmpdir'
|
|
|
|
if Gitlab::Runtime.sidekiq?
|
|
Sidekiq.configure_server do |config|
|
|
config.on :startup do
|
|
on_worker_start
|
|
end
|
|
end
|
|
else
|
|
Gitlab::Cluster::LifecycleEvents.on_worker_start do
|
|
on_worker_start
|
|
end
|
|
end
|
|
end
|
|
|
|
def self.on_worker_start
|
|
log_event('listening for SIGUSR2 signal')
|
|
|
|
# create a pipe in order to propagate signal out of the signal handler
|
|
# see also: https://cr.yp.to/docs/selfpipe.html
|
|
read, write = IO.pipe
|
|
|
|
# create a separate thread that polls for signals on the pipe.
|
|
#
|
|
# this way we do not execute in signal handler context, which
|
|
# lifts restrictions and also serializes the calls in a thread-safe
|
|
# manner.
|
|
#
|
|
# it's very similar to a goroutine and channel design.
|
|
#
|
|
# another nice benefit of this method is that we can timeout the
|
|
# IO.wait_readable call, allowing the profile to automatically stop after
|
|
# a given interval (by default 30 seconds), avoiding unbounded memory
|
|
# growth from a profile that was started and never stopped.
|
|
t = Thread.new do
|
|
timeout_s = ENV['STACKPROF_TIMEOUT_S']&.to_i || DEFAULT_TIMEOUT_SEC
|
|
current_timeout_s = nil
|
|
loop do
|
|
read.getbyte if read.wait_readable(current_timeout_s)
|
|
|
|
if ::StackProf.running?
|
|
stackprof_file_prefix = ENV['STACKPROF_FILE_PREFIX'] || DEFAULT_FILE_PREFIX
|
|
stackprof_out_file = "#{stackprof_file_prefix}/stackprof.#{Process.pid}.#{SecureRandom.hex(6)}.profile"
|
|
|
|
log_event(
|
|
'stopping profile',
|
|
profile_filename: stackprof_out_file,
|
|
profile_timeout_s: timeout_s
|
|
)
|
|
|
|
::StackProf.stop
|
|
::StackProf.results(stackprof_out_file)
|
|
current_timeout_s = nil
|
|
else
|
|
mode = ENV['STACKPROF_MODE']&.to_sym || DEFAULT_MODE
|
|
stackprof_interval = ENV['STACKPROF_INTERVAL']&.to_i
|
|
stackprof_interval ||= interval(mode)
|
|
|
|
log_event(
|
|
'starting profile',
|
|
profile_mode: mode,
|
|
profile_interval: stackprof_interval,
|
|
profile_timeout: timeout_s
|
|
)
|
|
|
|
::StackProf.start(
|
|
mode: mode,
|
|
raw: Gitlab::Utils.to_boolean(ENV['STACKPROF_RAW'] || 'true'),
|
|
interval: stackprof_interval
|
|
)
|
|
current_timeout_s = timeout_s
|
|
end
|
|
end
|
|
rescue StandardError => e
|
|
log_event("stackprof failed: #{e}")
|
|
end
|
|
t.abort_on_exception = true
|
|
|
|
# in the case of puma, this will override the existing SIGUSR2 signal handler
|
|
# that can be used to trigger a restart.
|
|
#
|
|
# puma cluster has two types of restarts:
|
|
# * SIGUSR1: phased restart
|
|
# * SIGUSR2: restart
|
|
#
|
|
# phased restart is not supported in our configuration, because we use
|
|
# preload_app. this means we will always perform a normal restart.
|
|
# additionally, phased restart is not supported when sending a SIGUSR2
|
|
# directly to a puma worker (as opposed to the master process).
|
|
#
|
|
# the result is that the behaviour of SIGUSR1 and SIGUSR2 is identical in
|
|
# our configuration, and we can always use a SIGUSR1 to perform a restart.
|
|
#
|
|
# thus, it is acceptable for us to re-appropriate the SIGUSR2 signal, and
|
|
# override the puma behaviour.
|
|
#
|
|
# see also:
|
|
# * https://github.com/puma/puma/blob/master/docs/signals.md#puma-signals
|
|
# * https://github.com/mperham/sidekiq/wiki/Signals
|
|
Signal.trap('SIGUSR2') do
|
|
write.write('.')
|
|
end
|
|
end
|
|
|
|
def self.log_event(event, labels = {})
|
|
Gitlab::AppJsonLogger.info({
|
|
event: 'stackprof',
|
|
message: event,
|
|
pid: Process.pid
|
|
}.merge(labels.compact))
|
|
end
|
|
|
|
def self.interval(mode)
|
|
mode == :object ? DEFAULT_INTERVAL_EVENTS : DEFAULT_INTERVAL_US
|
|
end
|
|
end
|
|
end
|