[HADOOP-10077] o.a.h.s.Groups should refresh in the background

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.3.0
• Target Version/s: 2.3.0
• Assignee: Colin McCabe
• Reporter: Colin McCabe
• Created: 30/Oct/13 23:37
• Updated: 04/Dec/14 21:35
• Resolved: 04/Dec/14 21:35

Description

org.apache.hadoop.security.Groups maintains a cache of mappings between user names and sets of associated group names. Periodically, the entries in this cache expire and must be refetched from the operating system.

Currently, this is done in the context of whatever thread happens to try to access the group mapping information right after the time period expires. However, this is problematic, since that thread may be holding the FSNamesystem lock. This means that if the GroupMappingServiceProvider is slow, the whole NameNode may grind to a halt until it finishes. This can generate periodic load spikes or even NameNode failovers.

Instead, we should allow the refreshing of the group mappings to be done asynchronously in a background thread pool.

Issue Links

• duplicates: HADOOP-11238 Update the NameNode's Group Cache in the background when possible
• is related to: HADOOP-11238 Update the NameNode's Group Cache in the background when possible
• is related to: HADOOP-10079 log a warning message if group resolution takes too long.