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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
require 'benchmark'
require 'atomic'
require 'thread'
Thread.abort_on_exception = true
$go = false # for synchronizing parallel threads
# number of updates on the value
N = ARGV[1] ? ARGV[1].to_i : 100_000
# number of threads for parallel test
M = ARGV[0] ? ARGV[0].to_i : 100
puts "*** Sequential updates ***"
Benchmark.bm(10) do |x|
value = 0
x.report "no lock" do
N.times do
value += 1
end
end
@lock = Mutex.new
x.report "mutex" do
value = 0
N.times do
@lock.synchronize do
value += 1
end
end
end
@atom = Atomic.new(0)
x.report "atomic" do
N.times do
@atom.update{|x| x += 1}
end
end
end
def para_setup(num_threads, count, &block)
if num_threads % 2 > 0
raise ArgumentError, "num_threads must be a multiple of two"
end
raise ArgumentError, "need block" unless block_given?
# Keep those threads together
tg = ThreadGroup.new
num_threads.times do |i|
diff = (i % 2 == 0) ? 1 : -1
t = Thread.new do
nil until $go
count.times do
yield diff
end
end
tg.add(t)
end
# Make sure all threads are started
while tg.list.find{|t| t.status != "run"}
Thread.pass
end
# For good measure
GC.start
tg
end
def para_run(tg)
$go = true
tg.list.each{|t| t.join}
$go = false
end
puts "*** Parallel updates ***"
Benchmark.bm(10) do |bm|
# This is not secure
value = 0
tg = para_setup(M, N/M) do |diff|
value += diff
end
bm.report("no lock"){ para_run(tg) }
value = 0
@lock = Mutex.new
tg = para_setup(M, N/M) do |diff|
@lock.synchronize do
value += diff
end
end
bm.report("mutex"){ para_run(tg) }
raise unless value == 0
@atom = Atomic.new(0)
tg = para_setup(M, N/M) do |diff|
@atom.update{|x| x + diff}
end
bm.report("atomic"){ para_run(tg) }
raise unless @atom.value == 0
end
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