[MAPREDUCE-1914] TrackerDistributedCacheManager never cleans its input directories

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Assignee: Dick King
• Reporter: Dick King
• Created: 02/Jul/10 23:46
• Updated: 30/Jul/14 21:53
• Resolved: 30/Jul/14 21:53

Description

When we localize a file into a node's cache, it's installed in a directory whose subroot is a random long . These long s all sit in a single flat directory [per disk, per cluster node]. When the cached file is no longer needed, its reference count becomes zero in a tracking data structure. The file then becomes eligible for deletion when the total amount of space occupied by cached files exceeds 10G [by default] or the total number of such files exceeds 10K.

However, when we delete a cached file, we don't delete the directory that contains it; this importantly includes the elements of the flat directory, which then accumulate until they reach a system limit, 32K in some cases, and then the node stops working.

We need to delete the flat directory when we delete the localized cache file it contains.

Issue Links

• is related to: MAPREDUCE-1538 TrackerDistributedCacheManager can fail because the number of subdirectories reaches system limit
• is related to: MAPREDUCE-1909 TrackerDistributedCacheManager takes a blocking lock fo a loop that executes 10K times