[HDFS-9322] Keep order of addresses to nameservice mapping from configuration file

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.7.1
• Labels: has-patch
• Assignee: Rafal Wojdyla
• Reporter: Rafal Wojdyla
• Created: 28/Oct/15 05:57
• Updated: 29/Oct/15 09:18

Description

getAddressesForNameserviceId which is used by ConfiguredFailoverProxyProvider does not keep order of namenodes/addresses from configuration file - instead it relays on order given by HashMap (key is service id) which is misaligned with comment/doc in ConfiguredFailoverProxyProvider that says:

/**
 * A FailoverProxyProvider implementation which allows one to configure two URIs
 * to connect to during fail-over. The first configured address is tried first,
 * and on a fail-over event the other address is tried.
 */

One solution is to use LinkedHashMap which is insertion-ordered.