[HADOOP-3556] Substitute the synchronized code in MD5Hash to avoid lock contention. Use ThreadLocal instead.

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.19.0
• Component/s: io
• Hadoop Flags: Reviewed
• Assignee: Iván de Prado
• Reporter: Iván de Prado
• Created: 13/Jun/08 15:38
• Updated: 20/Nov/08 23:38
• Resolved: 30/Jun/08 17:52

Description

Currently the MD5Hash class uses a singleton instance of the MessageDigester. The access to this instance is synchronized, so MD5Hash has performance problems when used from several Threads. I propose to substitute the singleton instance by a TheadLocal instances cache. I will provide a patch.