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https://issues.apache.org/jira/browse/HADOOP-9601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13676068#comment-13676068
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Gopal V commented on HADOOP-9601:
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The JNI calls were in-place to allow mixtures of direct/array buffers to be
used (i.e checksums in one format & data in another).
But that doesn't look like a common scenario when I was testing this.
The exceptions can all be pulled out of the critical section, because they
don't have particularly much to do with the data loops - all exceptions cause
loop terminations, when we can release the objects and then throw.
I will move the cleanup to a macro and shove it in before every throw+return.
The GetPrimitiveArrayCritical chunking can be done easily within the loop, but
would it need independent JNI calls to unlock the GC? And if it does, in the
best case scenario that is choking the lock - but it won't stutter other
threads when given a particularly large array (128 Mb from the block pool
scanner?).
> Support native CRC on byte arrays
> ---------------------------------
>
> Key: HADOOP-9601
> URL: https://issues.apache.org/jira/browse/HADOOP-9601
> Project: Hadoop Common
> Issue Type: Improvement
> Components: performance, util
> Affects Versions: 3.0.0
> Reporter: Todd Lipcon
> Attachments: HADOOP-9601-WIP-01.patch
>
>
> When we first implemented the Native CRC code, we only did so for direct byte
> buffers, because these correspond directly to native heap memory and thus
> make it easy to access via JNI. We'd generally assumed that accessing byte[]
> arrays from JNI was not efficient enough, but now that I know more about JNI
> I don't think that's true -- we just need to make sure that the critical
> sections where we lock the buffers are short.
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