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capture_block_vs_yield.rb
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require 'benchmark/ips'
def yield_control
yield
end
def capture_block_and_yield(&block)
yield
end
def capture_block_and_call(&block)
block.call
end
puts "Using the block directly"
Benchmark.ips do |x|
x.report("yield ") do
yield_control { }
end
x.report("capture block and yield") do
capture_block_and_yield { }
end
x.report("capture block and call ") do
capture_block_and_call { }
end
end
puts "Forwarding the block to another method"
def tap_with_yield
5.tap { |i| yield i }
end
def tap_with_forwarded_block(&block)
5.tap(&block)
end
Benchmark.ips do |x|
x.report("tap { |i| yield i }") do
tap_with_yield { |i| }
end
x.report("tap(&block) ") do
tap_with_forwarded_block { |i| }
end
end
def yield_n_times(n)
n.times { yield }
end
def forward_block_to_n_times(n, &block)
n.times(&block)
end
def call_block_n_times(n, &block)
n.times { block.call }
end
[10, 25, 50, 100, 1000, 10000].each do |count|
puts "Invoking the block #{count} times"
Benchmark.ips do |x|
x.report("#{count}.times { yield } ") do
yield_n_times(count) { }
end
x.report("#{count}.times(&block) ") do
forward_block_to_n_times(count) { }
end
x.report("#{count}.times { block.call }") do
call_block_n_times(count) { }
end
end
end
__END__
This benchmark demonstrates that capturing a block (e.g. `&block`) has
a high constant cost, taking about 5x longer than a single `yield`
(even if the block is never used!).
However, forwarding a captured block can be faster than using `yield`
if the block is used many times (the breakeven point is at about 20-25
invocations), so it appears that he per-invocation cost of `yield`
is higher than that of a captured-and-forwarded block.
Note that there is no circumstance where using `block.call` is faster.
See also `flat_map_vs_inject.rb`, which appears to contradict these
results a little bit.
Using the block directly
Calculating -------------------------------------
yield
91.539k i/100ms
capture block and yield
50.945k i/100ms
capture block and call
50.923k i/100ms
-------------------------------------------------
yield
4.757M (± 6.0%) i/s - 23.709M
capture block and yield
1.112M (±20.7%) i/s - 5.349M
capture block and call
964.475k (±20.3%) i/s - 4.634M
Forwarding the block to another method
Calculating -------------------------------------
tap { |i| yield i } 74.620k i/100ms
tap(&block) 51.382k i/100ms
-------------------------------------------------
tap { |i| yield i } 3.213M (± 6.3%) i/s - 16.043M
tap(&block) 970.418k (±18.6%) i/s - 4.727M
Invoking the block 10 times
Calculating -------------------------------------
10.times { yield }
49.151k i/100ms
10.times(&block)
40.682k i/100ms
10.times { block.call }
27.576k i/100ms
-------------------------------------------------
10.times { yield }
908.673k (± 4.9%) i/s - 4.571M
10.times(&block)
674.565k (±16.1%) i/s - 3.336M
10.times { block.call }
385.056k (±10.3%) i/s - 1.930M
Invoking the block 25 times
Calculating -------------------------------------
25.times { yield }
29.874k i/100ms
25.times(&block)
30.934k i/100ms
25.times { block.call }
17.119k i/100ms
-------------------------------------------------
25.times { yield }
416.342k (± 3.6%) i/s - 2.091M
25.times(&block)
446.108k (±10.6%) i/s - 2.227M
25.times { block.call }
201.264k (± 7.2%) i/s - 1.010M
Invoking the block 50 times
Calculating -------------------------------------
50.times { yield }
17.690k i/100ms
50.times(&block)
21.760k i/100ms
50.times { block.call }
9.961k i/100ms
-------------------------------------------------
50.times { yield }
216.195k (± 5.7%) i/s - 1.079M
50.times(&block)
280.217k (± 9.9%) i/s - 1.393M
50.times { block.call }
112.754k (± 5.6%) i/s - 567.777k
Invoking the block 100 times
Calculating -------------------------------------
100.times { yield }
10.143k i/100ms
100.times(&block)
13.688k i/100ms
100.times { block.call }
5.551k i/100ms
-------------------------------------------------
100.times { yield }
111.700k (± 3.6%) i/s - 568.008k
100.times(&block)
163.638k (± 7.7%) i/s - 821.280k
100.times { block.call }
58.472k (± 5.6%) i/s - 294.203k
Invoking the block 1000 times
Calculating -------------------------------------
1000.times { yield }
1.113k i/100ms
1000.times(&block)
1.817k i/100ms
1000.times { block.call }
603.000 i/100ms
-------------------------------------------------
1000.times { yield }
11.156k (± 8.4%) i/s - 56.763k
1000.times(&block)
18.551k (±10.1%) i/s - 92.667k
1000.times { block.call }
6.206k (± 3.5%) i/s - 31.356k
Invoking the block 10000 times
Calculating -------------------------------------
10000.times { yield }
113.000 i/100ms
10000.times(&block)
189.000 i/100ms
10000.times { block.call }
61.000 i/100ms
-------------------------------------------------
10000.times { yield }
1.150k (± 3.6%) i/s - 5.763k
10000.times(&block)
1.896k (± 6.9%) i/s - 9.450k
10000.times { block.call }
624.401 (± 3.0%) i/s - 3.172k