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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HADOOP-16011) OsSecureRandom very slow compared to other SecureRandom implementations
Date Sat, 15 Dec 2018 06:21:00 GMT
Todd Lipcon created HADOOP-16011:
------------------------------------

             Summary: 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


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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