From: "headius (Charles Nutter)" <headius@...>
Date: 2012-11-18T13:44:34+09:00
Subject: [ruby-core:49517] [ruby-trunk - Feature #6154] Eliminate extending WaitReadable/Writable at runtime


Issue #6154 has been updated by headius (Charles Nutter).


I have made the additional OpenSSL changes in the following JRuby commit: https://github.com/jruby/jruby/commit/8b022c896ea0d76f876e458229f4f150893295b9

The new exceptions are SSLErrorReadable and SSLErrorWritable. I am not married to these names, but unfortunately I do not wish to continue perpetuating the performance impact of extending these exceptions every time.

The current behavior of MRI to extend WaitReadable and WaitWritable every time is a *bug*. It needs to be fixed.
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Feature #6154: Eliminate extending WaitReadable/Writable at runtime
https://bugs.ruby-lang.org/issues/6154#change-33050

Author: headius (Charles Nutter)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: 


The nonblocking IO operations started extending WaitReadable or WaitWritable into the Errno::EAGAIN instance some time during the 1.9 series. This has a rather high cost, since a singleton class must be created and the global method cache must be flushed.

The attached patch instead creates two new classes of the following form, and raises them rather than raising a singleton EAGAIN:

class IO::EAGAINReadable < Errno::EAGAIN
  include WaitReadable
end

class IO::EAGAINWritable < Errno::EAGAIN
  include WaitWritable
end

The performance of repeatedly doing unsuccessful nonblocking reads improves by about 20%:

BEFORE:

system ~/projects/ruby $ ./ruby2.0.0 -rbenchmark -rsocket -e "sock = TCPSocket.new('localhost', 22); 10.times { puts Benchmark.measure { 100_000.times { begin; sock.read_nonblock(10); rescue IO::WaitReadable; end } } }"
  1.210000   0.110000   1.320000 (  1.328921)
  1.220000   0.120000   1.340000 (  1.326136)
  1.220000   0.110000   1.330000 (  1.334026)
  1.230000   0.110000   1.340000 (  1.349927)
  1.310000   0.130000   1.440000 (  1.426608)
  1.210000   0.110000   1.320000 (  1.333530)
  1.220000   0.120000   1.340000 (  1.330352)
  1.230000   0.110000   1.340000 (  1.350455)
  1.220000   0.120000   1.340000 (  1.327550)
  1.220000   0.110000   1.330000 (  1.337785)

AFTER:

system ~/projects/ruby $ ./ruby2.0.0 -rbenchmark -rsocket -e "sock = TCPSocket.new('localhost', 22); 10.times { puts Benchmark.measure { 100_000.times { begin; sock.read_nonblock(10); rescue IO::WaitReadable; end } } }"
  0.980000   0.110000   1.090000 (  1.092166)
  1.010000   0.120000   1.130000 (  1.129877)
  1.090000   0.120000   1.210000 (  1.202066)
  0.960000   0.110000   1.070000 (  1.076274)
  0.970000   0.100000   1.070000 (  1.078000)
  0.970000   0.110000   1.080000 (  1.078156)
  0.970000   0.110000   1.080000 (  1.078005)
  0.970000   0.110000   1.080000 (  1.078266)
  0.980000   0.110000   1.090000 (  1.093039)
  1.000000   0.110000   1.110000 (  1.112519)

This benchmark does not show the hidden cost of constantly invalidating the global method cache.

I also modified a similar case in OpenSSL, where it previously created an SSLError and extended WaitReadable into it.


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