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https://issues.apache.org/jira/browse/HADOOP-15033?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16251631#comment-16251631
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Dmitry Chuyko edited comment on HADOOP-15033 at 11/17/17 9:24 AM:
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It worths mentioning here that java.util.zip pure Java implementation compiled
by C2 without some inlining is ~2x slower for len=512 than Hadoop's pure Java
though they basically use the same approach to calculation. It is a subject for
improvement in core library for platforms and JVMS that don't provide CRC
intrinsics. But again in real life on Hotspot on x86 and aarch64 you always get
an intrinsic implementation.
was (Author: dchuyko):
It worths mentioning here that java.util.zip pure Java implementation compiled
by C2 is ~2x slower for len=512 than Hadoop's pure Java though they basically
use the same approach to calculation. It is a subject for improvement in core
library for platforms and JVMS that don't provide CRC intrinsics. But again in
real life on Hotspot on x86 and aarch64 you always get an intrinsic
implementation.
> Use java.util.zip.CRC32C for Java 9 and above
> ---------------------------------------------
>
> Key: HADOOP-15033
> URL: https://issues.apache.org/jira/browse/HADOOP-15033
> Project: Hadoop Common
> Issue Type: Improvement
> Components: performance, util
> Affects Versions: 3.0.0
> Reporter: Dmitry Chuyko
>
> java.util.zip.CRC32C implementation is available since Java 9.
> https://docs.oracle.com/javase/9/docs/api/java/util/zip/CRC32C.html
> Platform specific assembler intrinsics make it more effective than any pure
> Java implementation.
> Hadoop is compiled against Java 8 but class constructor may be accessible
> with method handle on 9 to instances implementing Checksum in runtime.
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