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  1. Hadoop HDFS
  2. HDFS-43

Ignoring IOExceptions on close

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Details

    • Bug
    • Status: Resolved
    • Critical
    • Resolution: Not A Problem
    • None
    • None
    • None
    • None

    Description

      Currently in HDFS there are a lot of calls to IOUtils.closeStream that are from finally blocks. I'm worried that this can lead to data corruption in the file system. Take the first instance in DataNode.copyBlock: it writes the block and then calls closeStream on the output stream. If there is an error at the end of the file that is detected in the close, it will be completely ignored. Note that logging the error is not enough, the error should be thrown so that the client knows the failure happened.

         try {
           file1.write(...);
           file2.write(...);
         } finally {
            IOUtils.closeStream(file);
        }
      

      is bad. It must be rewritten as:

         try {
           file1.write(...);
           file2.write(...);
           file1.close(...);
           file2.close(...);
         } catch (IOException ie) {
           IOUtils.closeStream(file1);
           IOUtils.closeStream(file2);
           throw ie;
         }
      

      I also think that IOUtils.closeStream should be renamed IOUtils.cleanupFailedStream or something to make it clear it can only be used after the write operation has failed and is being cleaned up.

      Attachments

        1. closeStream.patch
          2 kB
          Dhruba Borthakur

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            dhruba Dhruba Borthakur
            omalley Owen O'Malley
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              Updated:
              Resolved:

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