在许多线程中运行时出现"名称或服务未知(SocketError)"错误

Question

我制作了一个解析文本文件和并行下载数据的程序.当在9个或更少的线程中运行下载方法时,程序没有错误.但是当在10个或更多线程中运行该方法时,程序抛出"`initialize":getaddrinfo:名称或服务未知(SocketError)"错误.我尝试了一些并行运行的算法,但同样的问题也出现了.当将"名称或服务未知"错误发生时,我将传递给'open'方法(open-uri)的url放入浏览器并确认此url有效并收到正确的数据.这是部分代码.

jobs = []
aps = []
....
#jobs are pushed into jobs[]
....
max_thread = 15
loop do
  ary_threads = []
  max_thread.times do |i|
    break if jobs.size == 0
    job =  jobs.pop
    ary_threads << Thread.start {
      begin
        request(job[0],job[1]).each do |ap| #in "request" method, open(url)are called
            aps.push(ap)
        end
      end
    }
 end
 ary_threads.each { |th| th.join }
 break if jobs.size == 0
end

而错误是

/usr/lib/ruby/1.9.1/net/http.rb:762:in `initialize': getaddrinfo: Name or service not known (SocketError)
from /usr/lib/ruby/1.9.1/net/http.rb:762:in `open'
from /usr/lib/ruby/1.9.1/net/http.rb:762:in `block in connect'
from /usr/lib/ruby/1.9.1/timeout.rb:54:in `timeout'
from /usr/lib/ruby/1.9.1/timeout.rb:99:in `timeout'
from /usr/lib/ruby/1.9.1/net/http.rb:762:in `connect'
from /usr/lib/ruby/1.9.1/net/http.rb:755:in `do_start'
from /usr/lib/ruby/1.9.1/net/http.rb:744:in `start'
from /usr/lib/ruby/1.9.1/open-uri.rb:306:in `open_http'
from /usr/lib/ruby/1.9.1/open-uri.rb:775:in `buffer_open'
from /usr/lib/ruby/1.9.1/open-uri.rb:203:in `block in open_loop'
from /usr/lib/ruby/1.9.1/open-uri.rb:201:in `catch'
from /usr/lib/ruby/1.9.1/open-uri.rb:201:in `open_loop'
from /usr/lib/ruby/1.9.1/open-uri.rb:146:in `open_uri'
from /var/lib/gems/1.9.1/gems/open-uri-cached-0.0.5/lib/open-uri/cached.rb:10:in `open_uri'
from /usr/lib/ruby/1.9.1/open-uri.rb:677:in `open'
from /usr/lib/ruby/1.9.1/open-uri.rb:33:in `open'
from Test1.rb:42:in `request'
from Test1.rb:77:in `block (3 levels) in <main>'

为什么会这样？有谁遇到过类似的问题？请帮我!

第一个问题后3小时,我找到了临时解决方案.如果我在'begin'方法中将'open'方法与'begin~scue-retry~end'夹在一起,那么第二次'open'调用时就不会发生错误.这就是代码.

begin
    response = open(url)
rescue Exception
    puts url
    puts "retrying"
    retry
end

在捕获异常并显示url并"重试"之后,url和"retrying"将永远不会显示并且程序正常运行:)但仍然无法找到导致此问题的原因.

Answer 1

我认为这可能是因为线程之间的竞争条件。尝试以原子方式执行操作。放置互斥锁。

    @mutex = Mutex.new

    @mutex.syncronize do
      ...

      ary_threads << Thread.start {
       begin
        request(job[0],job[1]).each do |ap| #in "request" method, open(url)are called
          aps.push(ap)
        end
        end
      }

      ...
    end