Question

我试图通过使用线程FTP连接来加速多个FTP下载。我的问题是我总是有线程挂起。我正在寻找一种干净的方式告诉FTP它需要重试ftp事务，或者至少知道FTP连接何时挂起。

在下面的代码中，我正在线程化5/6个单独的FTP连接，其中每个线程都有一个预期下载的文件列表。脚本完成后，一些线程挂起，无法连接。我使用变量@last_updated来表示上次成功下载的时间。如果当前时间+ 20秒超过@last_updated，则终止剩余的线程。还有更好的方法吗？

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 }

Answer 1

我的诀窍是使用ruby的Timeout.timeout来确保FTP连接没有挂起。

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

悬挂FTP下载导致我的线程似乎挂起。既然线程不再挂起，我可以使用更合适的方式来处理线程：

threads.each { |t| j.join }

而不是丑陋：

# 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 }

Ruby Net :: FTP超时线程

1 个答案: