[HADOOP-7878] Regression HADOOP-7777 switch changes break HDFS tests when the isSingleSwitch() predicate is used

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.23.0, 0.24.0
• Fix Version/s: 0.23.1
• Component/s: util
• Labels: regression
• Target Version/s: 0.23.1, 0.24.0
• Assignee: Steve Loughran
• Reporter: Steve Loughran
• Created: 02/Dec/11 15:06
• Updated: 10/Mar/15 02:09
• Resolved: 12/Dec/11 15:06

Description

This doesn't show up until you apply the HDFS-2492 patch, but the attempt to make the StaticMapping topology clever by deciding if it is single rack or multi rack based on its rack->node mapping breaks the HDFS TestBlocksWithNotEnoughRacks test. Why? Because the racks go in after the switch topology is cached by the BlockManager, which assumes the system is always single-switch.

Fix: default to assuming multi-switch; remove the intelligence, add a setter for anyone who really wants to simulate single-switch racks.

Test: verify that a newly created simple mapping is multi switch

Issue Links

• is depended upon by: HDFS-2492 BlockManager cross-rack replication checks only work for ScriptBasedMapping
• relates to: HADOOP-7777 Implement a base class for DNSToSwitchMapping implementations that can offer extra topology information