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Posted to common-issues@hadoop.apache.org by "Taro L. Saito (Jira)" <ji...@apache.org> on 2020/08/25 19:07:00 UTC
[jira] [Comment Edited] (HADOOP-17125) Using snappy-java in
SnappyCodec
[ https://issues.apache.org/jira/browse/HADOOP-17125?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17184686#comment-17184686 ]
Taro L. Saito edited comment on HADOOP-17125 at 8/25/20, 7:06 PM:
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I'm the creator of snappy-java and happy to see this change.
A couple of thoughts:
* snappy-java has pre-compiled binaries of Snappy for various platforms, which can be found from here [https://github.com/xerial/snappy-java/tree/master/src/main/resources/org/xerial/snappy/native]
* The PR uses only Snappy.compress, uncompress. This is a good idea as these APIs have not been changed for years and most stable ones. SnappyInput/OutputStreams uses snappy-java's own format, so sticking to Snappy.compress/uncompress would be ideal for the maintainability.
* A limitation of pure-java Snappy is that it doesn't support some big-endian architecture like IBM zOS/s390x [https://github.com/xerial/snappy-java/issues/232.|https://github.com/xerial/snappy-java/issues/232] Once we added a pre-compiled native library for it, we can support this platform as well. If supporting more wide varieties of big-endian platform will be necessary, we need to extend the aircompressor to support big-endian architecture.
was (Author: taroleo):
I'm the creator of snappy-java and happy to see this change.
A couple of thoughts:
* Currently, snappy-java has pre-compiled binaries of Snappy for various platforms, which can be found from here [https://github.com/xerial/snappy-java/tree/master/src/main/resources/org/xerial/snappy/native]
* The PR uses only Snappy.compress, uncompress. This is a good idea as these APIs have not been changed for years and most stable ones. SnappyInput/OutputStreams uses snappy-java's own format, so sticking to Snappy.compress/uncompress would be ideal for the maintainability.
* A limitation of pure-java Snappy is that it doesn't support some big-endian architecture like IBM zOS/s390x [https://github.com/xerial/snappy-java/issues/232.|https://github.com/xerial/snappy-java/issues/232] Once we added a pre-compiled native library for it, we can support this platform as well. If supporting more wide varieties of big-endian platform will be necessary, we need to extend the aircompressor to support big-endian architecture.
> Using snappy-java in SnappyCodec
> --------------------------------
>
> Key: HADOOP-17125
> URL: https://issues.apache.org/jira/browse/HADOOP-17125
> Project: Hadoop Common
> Issue Type: New Feature
> Components: common
> Affects Versions: 3.3.0
> Reporter: DB Tsai
> Priority: Major
>
> In Hadoop, we use native libs for snappy codec which has several disadvantages:
> * It requires native *libhadoop* and *libsnappy* to be installed in system *LD_LIBRARY_PATH*, and they have to be installed separately on each node of the clusters, container images, or local test environments which adds huge complexities from deployment point of view. In some environments, it requires compiling the natives from sources which is non-trivial. Also, this approach is platform dependent; the binary may not work in different platform, so it requires recompilation.
> * It requires extra configuration of *java.library.path* to load the natives, and it results higher application deployment and maintenance cost for users.
> Projects such as *Spark* and *Parquet* use [snappy-java|[https://github.com/xerial/snappy-java]] which is JNI-based implementation. It contains native binaries for Linux, Mac, and IBM in jar file, and it can automatically load the native binaries into JVM from jar without any setup. If a native implementation can not be found for a platform, it can fallback to pure-java implementation of snappy based on [aircompressor|[https://github.com/airlift/aircompressor/tree/master/src/main/java/io/airlift/compress/snappy]].
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