discourse/lib/middleware/unicorn_oobgc.rb

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# THIS FILE IS TO BE EXTRACTED FROM DISCOURSE IT IS LICENSED UNDER THE MIT LICENSE
#
# The MIT License (MIT)
#
# Copyright (c) 2013 Discourse
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
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# Hook into unicorn, unicorn middleware, not rack middleware
#
# Since we need no knowledge about the request we can simply
# hook unicorn
module Middleware::UnicornOobgc
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MIN_REQUESTS_PER_OOBGC = 3
# TUNE ME, for Discourse this number is good
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MIN_FREE_SLOTS = 50_000
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# The oobgc implementation is far more efficient in 2.1
# as we have a bunch of profiling hooks to hook it
# use @tmm1s implementation
def use_gctools?
if @use_gctools.nil?
@use_gctools =
if RUBY_VERSION >= "2.1.0"
require "gctools/oobgc"
true
else
false
end
end
@use_gctools
end
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def verbose(msg=nil)
@verbose ||= ENV["OOBGC_VERBOSE"] == "1" ? :true : :false
if @verbose == :true
if(msg)
puts msg
end
true
end
end
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def self.init
# hook up HttpServer intercept
ObjectSpace.each_object(Unicorn::HttpServer) do |s|
s.extend(self)
end
rescue
puts "Attempted to patch Unicorn but it is not loaded"
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end
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# the closer this is to the GC run the more accurate it is
def estimate_live_num_at_gc(stat)
stat[:heap_live_num] + stat[:heap_free_num]
end
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def process_client(client)
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if use_gctools?
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super(client)
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GC::OOB.run
return
end
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stat = GC.stat
@num_requests ||= 0
@num_requests += 1
gc_count = stat[:count]
live_num = stat[:heap_live_num]
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@expect_gc_at ||= estimate_live_num_at_gc(stat)
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super(client) # Unicorn::HttpServer#process_client
# at this point client is serviced
stat = GC.stat
new_gc_count = stat[:count]
new_live_num = stat[:heap_live_num]
# no GC happened during the request
if new_gc_count == gc_count
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delta = new_live_num - live_num
@max_delta ||= delta
if delta > @max_delta
new_delta = (@max_delta * 1.5).to_i
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@max_delta = [new_delta, delta].min
else
# this may seem like a very tiny decay rate, but some apps using caching
# can really mess stuff up, if our delta is too low the algorithm fails
new_delta = (@max_delta * 0.99).to_i
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@max_delta = [new_delta, delta].max
end
if @max_delta < MIN_FREE_SLOTS
@max_delta = MIN_FREE_SLOTS
end
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if @num_requests > MIN_REQUESTS_PER_OOBGC && @max_delta * 2 + new_live_num > @expect_gc_at
t = Time.now
GC.start
stat = GC.stat
@expect_gc_at = estimate_live_num_at_gc(stat)
verbose "OobGC hit pid: #{Process.pid} req: #{@num_requests} max delta: #{@max_delta} expect at: #{@expect_gc_at} #{((Time.now - t) * 1000).to_i}ms saved"
@num_requests = 0
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end
else
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verbose "OobGC miss pid: #{Process.pid} reqs: #{@num_requests} max delta: #{@max_delta}"
@num_requests = 0
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@expect_gc_at = estimate_live_num_at_gc(stat)
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end
end
end