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Posted to hdfs-issues@hadoop.apache.org by "John Carrino (JIRA)" <ji...@apache.org> on 2011/04/19 06:30:05 UTC
[jira] [Commented] (HDFS-1835) DataNode.setNewStorageID pulls
entropy from /dev/random
[ https://issues.apache.org/jira/browse/HDFS-1835?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13021404#comment-13021404 ]
John Carrino commented on HDFS-1835:
------------------------------------
by 120 bits, I mean 160 bits. 20 bytes.
> DataNode.setNewStorageID pulls entropy from /dev/random
> -------------------------------------------------------
>
> Key: HDFS-1835
> URL: https://issues.apache.org/jira/browse/HDFS-1835
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: data-node
> Affects Versions: 0.20.2
> Reporter: John Carrino
> Original Estimate: 10m
> Remaining Estimate: 10m
>
> 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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