Kai X created HADOOP-16018:
------------------------------
Summary: DistCp won't reassemble chunks when blocks per chunk > 0
Key: HADOOP-16018
URL: https://issues.apache.org/jira/browse/HADOOP-16018
Project: Hadoop Common
Issue Type: Bug
Components: tools/distcp
Affects Versions: 3.0.3, 2.9.2, 3.1.1
Reporter: Kai X
I was investigating why hadoop-distcp-2.9.2 won't reassemble chunks of the same
file when blocks per chunk has been set > 0.
In the CopyCommitter::commitJob, this logic can prevent reassemble chunks if
blocks per chunk is equal to 0:
{code:java}
if (blocksPerChunk > 0) {
concatFileChunks(conf);
}
{code}
Then in CopyCommitter's ctor, blocksPerChunk is initialised from the config:
{code:java}
blocksPerChunk = context.getConfiguration().getInt(
DistCpOptionSwitch.BLOCKS_PER_CHUNK.getConfigLabel(), 0);
{code}
But here the config key DistCpOptionSwitch.BLOCKS_PER_CHUNK.getConfigLabel()
will always returns empty string because it is constructed without config label:
{code:java}
BLOCKS_PER_CHUNK("",
new Option("blocksperchunk", true, "If set to a positive value, files"
+ "with more blocks than this value will be split into chunks of "
+ "<blocksperchunk> blocks to be transferred in parallel, and "
+ "reassembled on the destination. By default, <blocksperchunk> is "
+ "0 and the files will be transmitted in their entirety without "
+ "splitting. This switch is only applicable when the source file "
+ "system implements getBlockLocations method and the target file "
+ "system implements concat method"))
{code}
As a result it will fall back to the default value 0 for blocksPerChunk, and
prevent the chunks from reassembling.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
