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https://issues.apache.org/jira/browse/HADOOP-7225?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13019688#comment-13019688
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John Carrino commented on HADOOP-7225:
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I think this may need to get filed under HDFS instead of Hadoop Common.
> DataNode.setNewStorageID pulls entropy from /dev/random
> -------------------------------------------------------
>
> Key: HADOOP-7225
> URL: https://issues.apache.org/jira/browse/HADOOP-7225
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 0.17.0
> Environment: linux
> Reporter: John Carrino
> Priority: Minor
> 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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