[jira] [Created] (HDFS-15442) dfs.image.transfer.chunksize should have check code before use

["AMC-team (Jira)" <ji...@apache.org>]

AMC-team created HDFS-15442:
-------------------------------

             Summary: dfs.image.transfer.chunksize should have check code before use
                 Key: HDFS-15442
                 URL: https://issues.apache.org/jira/browse/HDFS-15442
             Project: Hadoop HDFS
          Issue Type: Bug
            Reporter: AMC-team


In current implementation of checkpoint image transfer, if the file is bigger than the configured value dfs.image.transfer.chunksize. Then it will use chunked streaming mode to avoid internal buffering. This mode should be used only if more than chunkSize data is present to upload, otherwise upload may not happen sometimes.

{code:java}
//TransferFsImage.java
int chunkSize = (int) conf.getLongBytes(
    DFSConfigKeys.DFS_IMAGE_TRANSFER_CHUNKSIZE_KEY,
    DFSConfigKeys.DFS_IMAGE_TRANSFER_CHUNKSIZE_DEFAULT);
if (imageFile.length() > chunkSize) {
  // using chunked streaming mode to support upload of 2GB+ files and to
  // avoid internal buffering.
  // this mode should be used only if more than chunkSize data is present
  // to upload. otherwise upload may not happen sometimes.
  connection.setChunkedStreamingMode(chunkSize);
}
{code}

However, there is no any check code for this parameter. User may accidentally set this value to a wrong value. Here, if the user set chunkSize to a negative value. Chunked streaming mode will always be used. In setChunkedStreamingMode(chunkSize), there is a correction code that if the chunkSize is <=0, it will be change to DEFAULT_CHUNK_SIZE = 4096 (in bytes). 

{code:java}
public void setChunkedStreamingMode (int chunklen) {
    if (connected) {
        throw new IllegalStateException ("Can't set streaming mode: already connected");
    }
    if (fixedContentLength != -1 || fixedContentLengthLong != -1) {
        throw new IllegalStateException ("Fixed length streaming mode set");
    }
    chunkLength = chunklen <=0? DEFAULT_CHUNK_SIZE : chunklen;
}
{code}

However, the correction may be too late. If the user set dfs.image.transfer.chunksize to value that <= 0, even for images that imageFile.length() that < 4096 will use chunked streaming mode and may fail the upload as mentioned above. 

*How to fix:*

Add checking code or correction code right after parsing the config value before really use the value (if statement and setChunkedStreamingMode). 
 



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