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https://issues.apache.org/jira/browse/HADOOP-16011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16804354#comment-16804354
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Siyao Meng commented on HADOOP-16011:
-------------------------------------

[~jojochuang] I see no reference of OsSecureRandom in core-default.xml, only 
OpensslAesCtrCryptoCodec here:
{code:xml}
<property>
  <name>hadoop.security.crypto.codec.classes.aes.ctr.nopadding</name>
  <value>org.apache.hadoop.crypto.OpensslAesCtrCryptoCodec, 
org.apache.hadoop.crypto.JceAesCtrCryptoCodec</value>
  <description>
    Comma-separated list of crypto codec implementations for AES/CTR/NoPadding.
    The first implementation will be used if available, others are fallbacks.
  </description>
</property>
{code}
What change do we need here?

> OsSecureRandom very slow compared to other SecureRandom implementations
> -----------------------------------------------------------------------
>
>                 Key: HADOOP-16011
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16011
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>            Reporter: Todd Lipcon
>            Assignee: Siyao Meng
>            Priority: Major
>         Attachments: HADOOP-16011.001.patch, MyBenchmark.java
>
>
> In looking at performance of a workload which creates a lot of short-lived 
> remote connections to a secured DN, [~philip] and I found very high system 
> CPU usage. We tracked it down to reads from /dev/random, which are incurred 
> by the DN using CryptoCodec.generateSecureRandom to generate a transient 
> session key and IV for AES encryption.
> In the case that the OpenSSL codec is not enabled, the above code falls 
> through to the JDK SecureRandom implementation, which performs reasonably. 
> However, OpenSSLCodec defaults to using OsSecureRandom, which reads all 
> random data from /dev/random rather than doing something more efficient like 
> initializing a CSPRNG from a small seed.
> I wrote a simple JMH benchmark to compare various approaches when running 
> with concurrency 10:
>  testHadoop - using CryptoCodec
>  testNewSecureRandom - using 'new SecureRandom()' each iteration
>  testSha1PrngNew - using the SHA1PRNG explicitly, new instance each iteration
>  testSha1PrngShared - using a single shared instance of SHA1PRNG
>  testSha1PrngThread - using a thread-specific instance of SHA1PRNG
> {code:java}
> Benchmark                         Mode  Cnt        Score   Error  Units
> MyBenchmark.testHadoop           thrpt          1293.000          ops/s  
> [with libhadoop.so]
> MyBenchmark.testHadoop           thrpt        461515.697          ops/s 
> [without libhadoop.so]
> MyBenchmark.testNewSecureRandom  thrpt         43413.640          ops/s
> MyBenchmark.testSha1PrngNew      thrpt        395515.000          ops/s
> MyBenchmark.testSha1PrngShared   thrpt        164488.713          ops/s
> MyBenchmark.testSha1PrngThread   thrpt       4295123.210          ops/s
> {code}
> In other words, the presence of the OpenSSL acceleration slows down this code 
> path by 356x. And, compared to the optimal (thread-local Sha1Prng) it's 3321x 
> slower.



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