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From "Scott Carey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AVRO-1282) Make use of the sun.misc.Unsafe class during serialization if a JDK supports it
Date Mon, 22 Apr 2013 22:23:15 GMT

    [ https://issues.apache.org/jira/browse/AVRO-1282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13638507#comment-13638507
] 

Scott Carey commented on AVRO-1282:
-----------------------------------

Newer IBM JDK's seem to have Unsafe support -- so perhaps that is not the best example.  My
concern still stands -- how does this avoid failure when Unsafe does not exist?  I assume
that the presence of a static field of the type requires it to exist.
Other examples I can find seem to go different routes to protect form this case, and I don't
have access to a JVM without Unsafe to try it on.
                
> Make use of the sun.misc.Unsafe class during serialization if a JDK supports it
> -------------------------------------------------------------------------------
>
>                 Key: AVRO-1282
>                 URL: https://issues.apache.org/jira/browse/AVRO-1282
>             Project: Avro
>          Issue Type: Improvement
>          Components: java
>    Affects Versions: 1.7.4
>            Reporter: Leo Romanoff
>            Priority: Minor
>         Attachments: avro-1282-v1.patch, avro-1282-v2.patch, avro-1282-v3.patch, avro-1282-v4.patch,
avro-1282-v5.patch, avro-1282-v6.patch
>
>
> Unsafe can be used to significantly speed up serialization process, if a JDK implementation
supports java.misc.Unsafe properly. Most JDKs running on PCs support it. Some platforms like
Android lack a proper support for Unsafe yet.
> There are two possibilities to use Unsafe for serialization:
> 1) Very quick access to the fields of objects. It is way faster than with the reflection-based
approach using Field.get/set
> 2) Input and Output streams can be using Unsafe to perform very quick input/output.
>  
> 3) More over, Unsafe makes it possible to serialize to/deserialize from off-heap memory
directly and very quickly, without any intermediate buffers allocated on heap. There is virtually
no overhead compared to the usual byte arrays.

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