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ASF GitHub Bot commented on HADOOP-15033: ----------------------------------------- Github user aajisaka commented on a diff in the pull request: https://github.com/apache/hadoop/pull/291#discussion_r160858464 --- Diff: hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java --- @@ -43,6 +49,9 @@ public static final int CHECKSUM_CRC32C = 2; public static final int CHECKSUM_DEFAULT = 3; public static final int CHECKSUM_MIXED = 4; + + private static final Logger LOG = LoggerFactory.getLogger(DataChecksum.class); + private static volatile boolean useJava9Crc32C = Shell.isJavaVersionAtLeast(9); --- End diff -- @steveloughran @dchuyko The flag `useJava9Crc32C` can be final and I'm thinking changing it final also avoids synchronization. What do you think? Sorry for very late. > 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 > Labels: Java9, common, jdk9 > Attachments: HADOOP-15033.001.patch, HADOOP-15033.001.patch, > HADOOP-15033.002.patch, HADOOP-15033.003.patch, HADOOP-15033.003.patch, > HADOOP-15033.004.patch, HADOOP-15033.005.diff, HADOOP-15033.005.diff, > HADOOP-15033.005.diff, HADOOP-15033.005.patch, HADOOP-15033.006.patch, > HADOOP-15033.007.patch, HADOOP-15033.007.patch, HADOOP-15033.008.patch, > HADOOP-15033.009.patch, HADOOP-15033.009.patch, HADOOP-15033.009.patch, > HADOOP-15033.009.patch, HADOOP-15033.009.patch, HADOOP-15033.009.patch, > HADOOP-15033.009.patch, HADOOP-15033.010.patch > > > 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. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org