[HDFS-1835] DataNode.setNewStorageID pulls entropy from /dev/random

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.20.2
• Fix Version/s: 0.23.0
• Component/s: datanode
• Hadoop Flags: Reviewed
• Assignee: John Carrino
• Reporter: John Carrino
• Created: 14/Apr/11 04:38
• Updated: 15/Nov/11 00:52
• Resolved: 14/May/11 04:27

Description

DataNode.setNewStorageID uses SecureRandom.getInstance("SHA1PRNG") which always pulls fresh entropy.

It wouldn't be so bad if this were only the 120 bits needed by sha1, but the default impl of SecureRandom actually uses a BufferedInputStream around /dev/random and pulls 1024 bits of entropy for this one call.

If you are on a system without much entropy coming in, this call can block and block others.

Can we just change this to use "new SecureRandom().nextInt(Integer.MAX_VALUE)" instead?

Issue Links

• is related to: HDFS-2335 DataNodeCluster and NNStorage always pull fresh entropy