[HBASE-10413] Tablesplit.getLength returns 0

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.96.1.1
• Fix Version/s: 0.98.1, 0.99.0
• Component/s: Client, mapreduce
• Hadoop Flags: Reviewed
• Release Note: TableSplit.getLength() contains correct sizes of region in bytes. It is used by M/R framework for better scheduling.
• Assignee: Lukas Nalezenec
• Reporter: Lukas Nalezenec
• Created: 24/Jan/14 13:22
• Updated: 21/Feb/15 23:31
• Resolved: 10/Feb/14 22:31

Description

InputSplits should be sorted by length but TableSplit does not contain real getLength implementation:

@Override
public long getLength()

{ // Not clear how to obtain this... seems to be used only for sorting splits return 0; }

This is causing us problem with scheduling - we have got jobs that are supposed to finish in limited time but they get often stuck in last mapper working on large region.

Can we implement this method ?
What is the best way ?

We were thinking about estimating size by size of files on HDFS.
We would like to get Scanner from TableSplit, use startRow, stopRow and column families to get corresponding region than computing size of HDFS for given region and column family.

Update:
This ticket was about production issue - I talked with guy who worked on this and he said our production issue was probably not directly caused by getLength() returning 0.

Issue Links

• supercedes: HBASE-10019 PerfEval mapreduce percentage complete is inaccurate