编写使用Groovy（Grails的），以文件失败对于一些线（虚线） [英] Writing to file with Groovy(Grails) fails for some lines (broken lines)

问题描述

我在.csv文件中使用Groovy进行一些大规模的写作。更具体地讲，我有一个正在运行，并创建一个被发送到RabbitMQ的队列地图的一些消息的石英工作。队列正在由10名消费者，并导致生产串的某些列表耗尽。对于列表中的每个元素我只是把它写在管道分隔.csv文件。有一个写入.csv文件中的方法的实际服务，是一个标准的（单）交易Grails的服务。当我登录要写入的线条，一切都很好，但在文件中，一些线破。我写的方法是：

I am performing some mass writing in a .csv file using Groovy. More specifically, I have a Quartz job that is running and creates some Map messages that get sent to a RabbitMQ queue. The queue is being consumed by 10 consumers and results in producing some lists of Strings. For each element in the List I just write it in a pipe separated .csv file. The actual service that has the method that writes to the .csv file, is a standard (singleton) transactional grails service. When I log the lines to be written, everything's fine, but in the file, some lines are "broken". The way I am writing is:

def writeRowsToFile(List<String> rows, File file) {
  rows.each {row->
    file.append("${row}\n")
  }
}

起初我是用：

file.withWriterAppend {out->
  out.write(row.toString())
  out.newLine()
}

和得到了同样的事情，以及...

and got the same thing as well...

如果这是一件错了，它会失败的所有行。难道是某种竞争条件，并发或我不知道还有什么问题？

If it was something wrong it would fail for all the lines. Could it be some kind of race condition, concurrency or I don't know what else issue?

任何帮助将AP preciated。

Any help will be appreciated.

感谢

推荐答案

您应该做的是第二种方式，即：

You should be doing it the second way, ie:

def writeRowsToFile(List<String> rows, File file) {
  file.withWriterAppend {out->
    rows.eachWithIndex { row, idx ->

      // It's probably \n chars in your strings
      if( row ==~ /.*[\n\r]+.*/ ) {
        println "Detected a CRLF char in rows[$idx]"
      }

      out.writeLine row
    }
  }
}

不过，你说这可能是某种竞争状态

However, you say it might be "some kind of race condition"

多个线程写入同一个文件？

Are multiple threads writing to the same file?

如果不是，它更可能是你的行数据具有 \\ n 内的字符

If not, it is more likely that your row data has \n characters in it

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