[HADOOP-10353] FsUrlStreamHandlerFactory is not thread safe

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.0
• Fix Version/s: 2.4.0
• Component/s: fs
• Labels: race-condition
• Target Version/s: 2.4.0
• Hadoop Flags: Reviewed
• Assignee: Tudor Scurtu
• Reporter: Tudor Scurtu
• Created: 20/Feb/14 18:41
• Updated: 04/Sep/14 01:16
• Resolved: 27/Feb/14 19:17

Description

The FsUrlStreamHandlerFactory class uses a plain HashMap for caching.

When the number of inserted values exceeds the the map's load threshold, it triggers a rehash. During this time, a different thread that performs a get operation on a previously inserted key can obtain a null value instead of the actual value associated with that key.

The result is a NPE potentially being thrown when calling FsUrlStreamHandlerFactory#createURLStreamHandler(String protocol) concurrently.