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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