DataNode.setNewStorageID pulls entropy from /dev/random
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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
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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