ruby - IO错误 : closed stream in Ruby SFTP

Question

以下代码尝试通过 SFTP 和 Net::SFTP 列出远程目录的条目，但如果目录包含大量文件(~6000 个文件)，它会导致“关闭流”IOError:

require 'net/ssh'
require 'net/sftp'
Net::SFTP.start('hostname', 'username', :password => 'password') do |sftp|
  # list the entries in a directory
  sftp.dir.foreach("/") do |entry|
    puts entry.longname
  end
end 

避免它的最佳方法是什么？版本是 net-sftp Gem:2.0.5 和 net-ssh Gem:2.2.1，Ruby:1.8.7。完整的错误信息如下:

IOError: closed stream
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/ruby_compat.rb:33:in `select'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/ruby_compat.rb:33:in `io_select'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/ruby_compat.rb:32:in `synchronize'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/ruby_compat.rb:32:in `io_select'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/transport/packet_stream.rb:73:in `available_for_read?'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/transport/packet_stream.rb:85:in `next_packet'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/transport/session.rb:170:in `poll_message'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/transport/session.rb:165:in `loop'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/transport/session.rb:165:in `poll_message'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/connection/session.rb:451:in `dispatch_incoming_packets'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/connection/session.rb:213:in `preprocess'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/connection/session.rb:197:in `process'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/connection/session.rb:161:in `loop'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/connection/session.rb:161:in `loop_forever'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/connection/session.rb:161:in `loop'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-ssh-2.2.1/lib/net/ssh/connection/session.rb:110:in `close'
from ~/.rvm/gems/ruby-1.8.7-p330/gems/net-sftp-2.0.5/lib/net/sftp.rb:36:in `start'

Answer 1

如果我们看一下 net-sftp/lib/net/sftp/operations/dir.rb 中的 dir 源代码，这种行为可能是故意的，我们看到一个关闭操作:

def foreach(path)
  ..  
ensure
  sftp.close!(handle) if handle
end

有可能是这个close操作导致了closed stream的错误。如果它不表示错误，则可能捕获 IOError 异常。偶尔运行 SSH 事件循环似乎也有帮助:

begin   
  ..
  sftp.dir.foreach("/") do |entry|
    puts entry.longname
    # ...
    sftp.loop # Runs the SSH event loop 
  end
rescue IOError => Ex   
  puts "*** We are done: "+Ex.message 
end