[ https://issues.apache.org/jira/browse/HBASE-13382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14393323#comment-14393323 ]
Dima Spivak commented on HBASE-13382: ------------------------------------- Want me to take this, [~tlipcon]? Looks like a one line fix. > IntegrationTestBigLinkedList should use SecureRandom > ---------------------------------------------------- > > Key: HBASE-13382 > URL: https://issues.apache.org/jira/browse/HBASE-13382 > Project: HBase > Issue Type: Bug > Components: integration tests > Reporter: Todd Lipcon > > IntegrationTestBigLinkedList currently uses java.util.Random to generate its > random keys. The keys are 128 bits long, but we generate them using > Random.nextBytes(). The Random implementation itself only has a 48-bit seed, > so even though we have a very long key string, it doesn't have anywhere near > that amount of entropy. > This means that after a few billion rows, it's quite likely to run into a > collision: filling in a 16-byte key is equivalent to four calls to > rand.nextInt(). So, for 10B rows, we are cycling through 40B different 'seed' > values. With a 48-bit seed, it's quite likely we'll end up using the same > seed twice, after which point any future rows generated by the colliding > mappers are going to be equal. This results in broken chains and a failed > verification job. > The fix is simple -- we should use SecureRandom to generate the random keys, > instead. -- This message was sent by Atlassian JIRA (v6.3.4#6332)