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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3890) Use of CredentialProvider results in a lot of NN ops
Date Wed, 10 Jun 2015 21:57:01 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14581141#comment-14581141
] 

Josh Elser commented on ACCUMULO-3890:
--------------------------------------

Looked over ACCUMULO-3890.4.patch.

Given the assumption that we don't care about creating duplicate instances of a CP, I think
the synchronization on getCredentialProviders can be dropped. Like Sean pointed out, it's
already not threadsafe. My gut reaction is that this isn't in a "hot" enough code path that
it isn't significant enough to microbenchmark differing synchronization patterns.

My first reaction was that it might be better to make the cache a ConcurrentHashMap, but I
can't really come up with a good reason to do so. If we want to be safe, just synchronize
on the HashMap before getting or putting. Again, my guess is that it wouldn't have a big net
difference.


> Use of CredentialProvider results in a lot of NN ops
> ----------------------------------------------------
>
>                 Key: ACCUMULO-3890
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3890
>             Project: Accumulo
>          Issue Type: Bug
>    Affects Versions: 1.6.1, 1.6.2, 1.7.0
>            Reporter: Billie Rinaldi
>            Assignee: Billie Rinaldi
>             Fix For: 1.7.1, 1.8.0
>
>         Attachments: ACCUMULO-3890.1.patch, ACCUMULO-3890.2.patch, ACCUMULO-3890.3.patch,
ACCUMULO-3890.4.patch
>
>
> Every time we access a sensitive property or iterate over a configuration when there
is a CredentialProvider configured, it results in NN operations (as evidenced by FSNamesystem.audit
logs).  I think that we could assume the CredentialProvider is static, read its properties
once and cache them in memory to avoid these unnecessary reads.



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