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From "John Carrino (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HADOOP-7226) CLONE - DataNode.setNewStorageID pulls entropy from /dev/random
Date Thu, 14 Apr 2011 04:36:05 GMT
CLONE - DataNode.setNewStorageID pulls entropy from /dev/random
---------------------------------------------------------------

                 Key: HADOOP-7226
                 URL: https://issues.apache.org/jira/browse/HADOOP-7226
             Project: Hadoop Common
          Issue Type: Bug
          Components: fs
    Affects Versions: 0.17.0
         Environment: linux
            Reporter: John Carrino
            Priority: Minor


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?


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