红宝石的Net :: FTP超时主题(Ruby Net::FTP Timeout Threads)

我试图用螺纹FTP连接，加快多个FTP下载。我的问题是，我总是有线程挂起。我要寻找任何能说明FTP的一个干净的方式，它需要重试FTP交易，或当FTP连接挂至少知道。

在下面的代码，我穿5/6独立的FTP连接，每个线程都有它预计将下载的文件列表。脚本完成时，几个线程挂起，不能加入。我使用@last_updated表示上次成功下载的时间变量。如果当前时间+20秒超过设定的@last_updated，杀死剩余线程。有没有更好的办法？

threads = []
max_thread_pool = 5
running_threads = 0
Thread.abort_on_exception = true

existing_file_count = 0
files_downloaded = 0

errors = []
missing_on_the_server = []
@last_updated = Time.now

if ids.length > 0
    ids.each_slice(ids.length / max_thread_pool) do |id_set|
        threads << Thread.new(id_set) do |t_id_set|
            running_threads += 1
            thread_num = running_threads
            thread_num.freeze
            puts "making thread # #{thread_num}"
            begin
                ftp = Net::FTP.open(@remote_site)
                ftp.login(@remote_user, @remote_password)
                ftp.binary = true
                #ftp.debug_mode = true
                ftp.passive = false
            rescue
                raise "Could not establish FTP connection"
            end
            t_id_set.each do |id|
                @last_updated = Time.now
                rmls_path = "/_Photos/0#{id[0,2]}00000/#{id[2,1]}0000/#{id[3,1]}000/#{id}-1.jpg"
                local_path = "#{@photos_path}/01/#{id}-1.jpg"
                progress += 1
                unless File.exist?(local_path)
                    begin
                        ftp.getbinaryfile(rmls_path, local_path)
                        puts "ftp reponse: #{ftp.last_response}"
                        # find the percentage of progress just for fun
                        files_downloaded += 1
                        p = sprintf("%.2f", ((progress.to_f / total) * 100))
                        puts "Thread # #{thread_num} > %#{p} > #{progress}/#{total} > Got file: #{local_path}"
                    rescue
                        errors << "#{thread_num} unable to get file > ftp response: #{ftp.last_response}"
                        puts errors.last
                        if ftp.last_response_code.to_i == 550
                            # Add the missing file to the missing list
                            missing_on_the_server << errors.last.match(/\d{5,}-\d{1,2}\.jpg/)[0]
                        end
                    end
                else
                    puts "found file: #{local_path}"
                    existing_file_count += 1
                end
            end
            puts "closing FTP connection #{thread_num}"
            ftp.close
        end # close thread
    end
end

# If @last_updated has not been updated on the server in over 20 seconds, wait 3 seconds and check again
while Time.now < @last_updated + 20 do
    sleep 3
end
# threads are hanging so joining the threads does not work.
threads.each { |t| t.kill }

对于我这种工作的诀窍是使用红宝石的Timeout.timeout，确保FTP连接未挂。

begin
    Timeout.timeout(10) do
        ftp.getbinaryfile(rmls_path, local_path)
    end
    # ...
rescue Timeout::Error
    errors << "#{thread_num}> File download timed out for: #{rmls_path}"
    puts errors.last
rescue
    errors << "unable to get file > ftp reponse: #{ftp.last_response}"
    # ...
end

挂FTP下载是导致我的线程似乎挂起。现在，线程不再挂，我可以使用处理线程的更正确的方法：

threads.each { |t| j.join }

而不是丑：

# If @last_updated has not been updated on the server in over 20 seconds, wait 3 seconds and check again
while Time.now < @last_updated + 20 do
    sleep 3
end
# threads are hanging so joining the threads does not work.
threads.each { |t| t.kill }