Andrew Wang created HDFS-12222:
----------------------------------
Summary: Add EC information to BlockLocations
Key: HDFS-12222
URL: https://issues.apache.org/jira/browse/HDFS-12222
Project: Hadoop HDFS
Issue Type: Bug
Affects Versions: 3.0.0-alpha1
Reporter: Andrew Wang
HDFS applications query block location information to compute splits. One
example of this is FileInputFormat:
https://github.com/apache/hadoop/blob/d4015f8628dd973c7433639451a9acc3e741d2a2/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/FileInputFormat.java#L346
You see bits of code like this that calculate offsets as follows:
{noformat}
long bytesInThisBlock = blkLocations[startIndex].getOffset() +
blkLocations[startIndex].getLength() - offset;
{noformat}
EC confuses this since the block locations include parity block locations as
well, which are not part of the logical file length. This messes up the offset
calculation and thus topology/caching information too.
Applications can figure out what's a parity block by reading the EC policy and
then parsing the schema, but it'd be a lot better if we exposed this more
generically in BlockLocation instead.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-dev-unsubscr...@hadoop.apache.org
For additional commands, e-mail: hdfs-dev-h...@hadoop.apache.org
