Bug #13431: sample/drb/http0*.rb is not working.

• Status: Closed
• Assignee: seki (Masatoshi Seki)
• Target version: -
• ruby -v: ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16]
• Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN

[youchan (瑶 大崎)]

I tried to use drb over http with the sample code sample/drb/http0.rb*
I wrote the code as following.

server.rb

require 'drb/drb'
require_relative './http0serv'

class SampleObject
  def test
    "ACK!"
  end
end

DRb.start_service("http://127.0.0.1:1234", SampleObject.new)
DRb.thread.join

client.rb

require 'drb/drb'
require_relative './http0'

remote = DRbObject.new_with_uri "http://127.0.0.1:1234"

puts remote.test

This results in the following.

/Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/protocol.rb:176:in `rbuf_fill': Net::ReadTimeout (Net::ReadTimeout)
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/protocol.rb:154:in `readuntil'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/protocol.rb:164:in `readline'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http/response.rb:40:in `read_status_line'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http/response.rb:29:in `read_new'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1446:in `block in transport_request'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1443:in `catch'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1443:in `transport_request'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1416:in `request'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1409:in `block in request'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:877:in `start'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1407:in `request'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1430:in `send_entity'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/net/http.rb:1218:in `post'
        from /Users/youchan/Projects/tmp/drb_over_http/http0.rb:67:in `post'
        from /Users/youchan/Projects/tmp/drb_over_http/http0.rb:54:in `send_request'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/drb/drb.rb:1253:in `send_message'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/drb/drb.rb:1142:in `block (2 levels) in method_missing'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/drb/drb.rb:1229:in `open'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/drb/drb.rb:1141:in `block in method_missing'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/drb/drb.rb:1160:in `with_friend'
        from /Users/youchan/.rbenv/versions/2.4.1/lib/ruby/2.4.0/drb/drb.rb:1140:in `method_missing'
        from client.rb:6:in `<main>'

[znz (Kazuhiro NISHIYAMA)]

• Assignee set to seki (Masatoshi Seki)

以下のようにサーバーを起動して別端末で ruby -e '$LOAD_PATH.push "sample"' -e 'require "drb/http0"' -e 'remote = DRbObject.new_with_uri "http://127.0.0.1:12346"; puts remote.test' のように呼び出すと、以下のように client.uri で NoMethodError になるので、 r32254 の変更で動かなくなったようです。

% ruby -vdI lib -e '$LOAD_PATH.push "sample"' -e 'require "drb/http0serv"' -e 'class SampleObject;def test;"ACK!";end;end;DRb.start_service("http://127.0.0.1:12346", SampleObject.new); DRb.thread.join'
ruby 2.5.0dev (2017-04-18 trunk 58385) [x86_64-linux]
Exception `LoadError' at .../ruby/lib/rubygems.rb:1345 - cannot load such file -- rubygems/defaults/operating_system
Exception `LoadError' at .../ruby/lib/rubygems.rb:1354 - cannot load such file -- rubygems/defaults/ruby
Exception `DRb::DRbBadScheme' at .../ruby/lib/drb/drb.rb:826 - http://127.0.0.1:12346
Exception `NoMethodError' at .../ruby/lib/drb/drb.rb:1661 - undefined method `uri' for #<DRb::HTTP0::ServerSide:0x0000000002593b28>
Exception `NoMethodError' at -e:3 - undefined method `uri' for #<DRb::HTTP0::ServerSide:0x0000000002593b28>
127.0.0.1 - - [18/Apr/2017:21:31:19 JST] "POST / HTTP/1.1" 200 0
- -> /
        from .../ruby/lib/drb/drb.rb:1660:in `block in main_loop'
        from .../ruby/lib/drb/drb.rb:1660:in `synchronize'
.../ruby/lib/drb/drb.rb:1661:in `block (2 levels) in main_loop': undefined method `uri' for #<DRb::HTTP0::ServerSide:0x0000000002593b28> (NoMethodError)

[youchan (瑶 大崎)]

That is different from my case.

I forgot telling you the important fact.

• I copied files http0.rb, http0server.rb to working directory.
• I rewrote http0server.rb line 3, require 'drb/http0' to require_relative './http0'

And ran my scripts.

The results are as described above.

There seems to be a deadlock between the queue in server protocol and drb main loop.

I confirmed the program is blocked in

sample/drb/http0server.rb:28

and

drb/drb.rb:1660

   1655:       return nil if !client0
   1656:       Thread.start(client0) do |client|
   1657:         @grp.add Thread.current
   1658:         Thread.current['DRb'] = { 'client' => client ,
   1659:                                   'server' => self }
=> 1660:         DRb.mutex.synchronize do
   1661:           client_uri = client.uri
   1662:           @exported_uri << client_uri unless @exported_uri.include?(client_uri)
   1663:         end
   1664:         loop do

[shyouhei (Shyouhei Urabe)]

• Status changed from Open to Assigned

• Status changed from Assigned to Closed

Applied in changeset git|71d97a5ef80a23b0bb1005570ed059580981a467.

---

Fix sample/drb/http0serv.rb

Previously, trying to use this would result in:

undefined method `uri' for #DRb::HTTP0::ServerSide:0x00000aec9f1637f8 (NoMethodError)

Also, use a relative require to load sample/drb/http0.rb.

Fixes [Bug #13431]