Issue #16413 has been updated by naruse (Yui NARUSE).


履歴を見た感じ特に理由は無さそうですね。
https://github.com/ruby/ruby/pull/2737 で直りますでしょうか

----------------------------------------
Bug #16413: Net::FTP#put で書き込みエラーが発生した時のコネクション切断
https://bugs.ruby-lang.org/issues/16413#change-83065

* Author: koshigoe (Masataka SUZUKI)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.6.5p114 (2019-10-01 revision 67812) [x86_64-darwin18]
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
### 疑問

`Net::FTP#storbinary` などをみると、 `conn.write` で例外が発生した際に `conn.close` を呼ばない実装だと思います。
https://github.com/ruby/ruby/blob/7be550d046c726c2a3aa625ceb260d9b2268fb5a/lib/net/ftp.rb#L683-L707

一方で `Net::FTP#retrbinary` では `conn.shutdown` や `conn.close` (`ensure`) をしています。
https://github.com/ruby/ruby/blob/7be550d046c726c2a3aa625ceb260d9b2268fb5a/lib/net/ftp.rb#L629-L648

素人的な質問で恐縮ですが、これは意図的な実装でしょうか?

### 確認内容

適当な FTP サーバを起動。

```
$ docker run --rm \
  -p 20-21:20-21 \
  -p 21100-21110:21100-21110 \
  -e FTP_USER=user \
  -e FTP_PASS=pass \
  -e PASV_ADDRESS=localhost \
  -e PASV_MIN_PORT=21100 \
  -e PASV_MAX_PORT=21110 \
  fauria/vsftpd
```

`Net::FTP#put` のエラーを繰り返し発生させる。

```
require 'net/ftp'

def upload
  ftp = Net::FTP.new
  ftp.read_timeout = 0.1
  ftp.passive = true
  ftp.connect('localhost')
  ftp.login('user', 'pass')

  i = 0
  ftp.put(__FILE__, '/uploaded', 1) do |data|
    i += 1
    raise 'Bomb' if i > 3
  end
rescue => e
  puts e.message
ensure
  unless ftp.closed?
    ftp.close
    puts 'closed.'
  end
end

11.times { upload }

puts 'wait'
loop {}

__END__

Bomb
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
Net::ReadTimeout with #<Socket:fd 11>
closed.
wait
```

コネクションがたくさん作られる。

```
$ lsof -i:21100-21110
COMMAND     PID     USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
com.docke  1354 koshigoe   17u  IPv6 0x370c967258b56c15      0t0  TCP *:21110 (LISTEN)
com.docke  1354 koshigoe   19u  IPv6 0x370c967258b543d5      0t0  TCP *:21109 (LISTEN)
com.docke  1354 koshigoe   21u  IPv6 0x370c967258b56095      0t0  TCP *:21108 (LISTEN)
com.docke  1354 koshigoe   23u  IPv6 0x370c967258b55515      0t0  TCP *:21107 (LISTEN)
com.docke  1354 koshigoe   25u  IPv6 0x370c967258b53e15      0t0  TCP *:21106 (LISTEN)
com.docke  1354 koshigoe   29u  IPv6 0x370c967258b571d5      0t0  TCP *:21105 (LISTEN)
com.docke  1354 koshigoe   31u  IPv6 0x370c967256ed8e15      0t0  TCP *:21104 (LISTEN)
com.docke  1354 koshigoe   33u  IPv6 0x370c967256edb095      0t0  TCP *:21103 (LISTEN)
com.docke  1354 koshigoe   35u  IPv6 0x370c967256edaad5      0t0  TCP *:21102 (LISTEN)
com.docke  1354 koshigoe   37u  IPv6 0x370c967256ed93d5      0t0  TCP *:21101 (LISTEN)
com.docke  1354 koshigoe   39u  IPv6 0x370c967256ed9f55      0t0  TCP *:21100 (LISTEN)
com.docke  1354 koshigoe   45u  IPv6 0x370c967256eda515      0t0  TCP localhost:21105->localhost:61667 (ESTABLISHED)
com.docke  1354 koshigoe   47u  IPv6 0x370c967257775655      0t0  TCP localhost:21109->localhost:61669 (ESTABLISHED)
com.docke  1354 koshigoe   49u  IPv6 0x370c967257772855      0t0  TCP localhost:21107->localhost:61671 (ESTABLISHED)
com.docke  1354 koshigoe   51u  IPv6 0x370c9672434ea655      0t0  TCP localhost:21104->localhost:61673 (ESTABLISHED)
com.docke  1354 koshigoe   53u  IPv6 0x370c9672434e9515      0t0  TCP localhost:21106->localhost:61675 (ESTABLISHED)
com.docke  1354 koshigoe   55u  IPv6 0x370c967241a2b095      0t0  TCP localhost:21110->localhost:61677 (ESTABLISHED)
com.docke  1354 koshigoe   57u  IPv6 0x370c967241a2b655      0t0  TCP localhost:21102->localhost:61679 (ESTABLISHED)
com.docke  1354 koshigoe   59u  IPv6 0x370c967241a2c1d5      0t0  TCP localhost:21100->localhost:61681 (ESTABLISHED)
com.docke  1354 koshigoe   61u  IPv6 0x370c96725927f995      0t0  TCP localhost:21101->localhost:61683 (ESTABLISHED)
com.docke  1354 koshigoe   63u  IPv6 0x370c967259281095      0t0  TCP localhost:21103->localhost:61689 (ESTABLISHED)
com.docke  1354 koshigoe   65u  IPv6 0x370c967258b55ad5      0t0  TCP localhost:21108->localhost:61693 (ESTABLISHED)
ruby      75273 koshigoe   13u  IPv6 0x370c9672385ae1d5      0t0  TCP localhost:61667->localhost:21105 (ESTABLISHED)
ruby      75273 koshigoe   14u  IPv6 0x370c967256ed8855      0t0  TCP localhost:61669->localhost:21109 (ESTABLISHED)
ruby      75273 koshigoe   15u  IPv6 0x370c967257773f55      0t0  TCP localhost:61671->localhost:21107 (ESTABLISHED)
ruby      75273 koshigoe   16u  IPv6 0x370c9672434eac15      0t0  TCP localhost:61673->localhost:21104 (ESTABLISHED)
ruby      75273 koshigoe   17u  IPv6 0x370c9672434e8f55      0t0  TCP localhost:61675->localhost:21106 (ESTABLISHED)
ruby      75273 koshigoe   18u  IPv6 0x370c9672434e7855      0t0  TCP localhost:61677->localhost:21110 (ESTABLISHED)
ruby      75273 koshigoe   19u  IPv6 0x370c967241a2aad5      0t0  TCP localhost:61679->localhost:21102 (ESTABLISHED)
ruby      75273 koshigoe   20u  IPv6 0x370c967241a29995      0t0  TCP localhost:61681->localhost:21100 (ESTABLISHED)
ruby      75273 koshigoe   21u  IPv6 0x370c96725927ee15      0t0  TCP localhost:61683->localhost:21101 (ESTABLISHED)
ruby      75273 koshigoe   22u  IPv6 0x370c967259281c15      0t0  TCP localhost:61689->localhost:21103 (ESTABLISHED)
ruby      75273 koshigoe   23u  IPv6 0x370c967258b56655      0t0  TCP localhost:61693->localhost:21108 (ESTABLISHED)
```

FTP サーバ(vsftpd)のプロセスがたくさん作られる。

```
sh-4.1# ps aux | grep '[v]sftpd'
root         1  0.0  0.0  11368  2440 ?        Ss   09:01   0:00 /bin/bash -ex /usr/sbin/run-vsftpd.sh
root        13  0.0  0.1  52184  3864 ?        S    09:01   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3158  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3160  0.0  0.0  56684  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3161  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3163  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3164  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3166  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3167  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3169  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3170  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3172  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3173  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3175  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3176  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3178  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3179  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3181  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3182  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3184  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3185  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3187  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
nobody    3188  0.0  0.1  56584  3564 ?        Ss   09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
ftp       3190  0.0  0.0  56608  2432 ?        S    09:30   0:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
```



-- 
https://bugs.ruby-lang.org/