[jira] [Commented] (HADOOP-9857) Tests block and sometimes timeout on Windows due to invalid entropy source.

["Chris Nauroth (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-9857?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13735138#comment-13735138 ] 

Chris Nauroth commented on HADOOP-9857:
---------------------------------------

This relates back to HADOOP-7335 and HADOOP-7841, which started passing {{-Djava.security.egd=file:///dev/urandom}}.  Officially, documentation says that we're supposed to use {{file:/dev/urandom}}, but according to this comment, that didn't work as expected on Linux:

https://issues.apache.org/jira/browse/HADOOP-7335?focusedCommentId=13042504&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13042504

Instead, we needed {{file:///dev/urandom}} to get the behavior that we want.

Unfortunately, this causes bad side effects on Windows, because the JVM tries to do an exact string match on "file:/dev/urandom" in logic for selecting the native entropy provider on Windows.  See line 256 here:

http://hg.openjdk.java.net/jdk6/jdk6/jdk/file/ffa98eed5766/src/share/classes/sun/security/provider/SunEntries.java

Also, see the logic starting at line 96 here:

http://hg.openjdk.java.net/jdk6/jdk6/jdk/file/ffa98eed5766/src/share/classes/sun/security/provider/SeedGenerator.java

By enabling {{-Djava.security.debug=all}}, I was able to see that it was entering the "Failed to create seed generator" code path after a 5-second delay.

The problem was made more obvious recently by the introduction of client ID in each RPC client instance.  This requires creation of a {{UUID}}, so creation of the first RPC client instance in a test would trigger the 5-second delay.

                
> Tests block and sometimes timeout on Windows due to invalid entropy source.
> ---------------------------------------------------------------------------
>
>                 Key: HADOOP-9857
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9857
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: build, test
>    Affects Versions: 3.0.0, 2.1.1-beta
>            Reporter: Chris Nauroth
>            Assignee: Chris Nauroth
>
> Tests are configured to set the entropy source to {{file:///dev/urandom}} to prevent blocking on machines with low entropy.  We've observed that on Windows, this will cause tests to block for 5 seconds trying to access this non-existent path the first time the process does something that needs entropy, such as using a {{SecureRandom}} or creating a {{UUID}}.  This can cause tests to fail due to timeouts.  In addition to the initial 5-second blocking, this causes the JVM to fall back to a slower, non-native seed generation implementation.

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