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Phabricator commented on HBASE-5074: ------------------------------------ mbautin has commented on the revision "[jira] [HBASE-5074] Support checksums in HBase block cache". @dhruba: some more comments inline. INLINE COMMENTS src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:451-452 Assign headerSize() to a local variable instead of calling it twice. src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:529-530 Call headerSize() once and store in a local variable. src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1232 do do -> do src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1642-1644 Store and reuse part of the previous error message. src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1636 Check if WARN level messages are enabled and only generate the message string in that case. src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1848 double semicolon (does not matter) src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV2.java:424 What if istream != istreamNoFsChecksum but istreamNoFsChecksum == null? src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java:3610-3612 Not sure how this is related to HBase-level checksum checking src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:265 Make this conf key a constant in HConstants src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:275 conf key -> HConstants src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:40-43 This is unnecessary because the default toString would do the same. src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:57-60 This is unnecessary because the default toString would do the same. src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:103-106 This is unnecessary because the default toString would do the same. src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:143-144 It looks like toString would to this. src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:179 Would not the built-in enum method valueOf do what this function is doing? src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockCompatibility.java:1 This file still seems to contain a lot of copy-and-paste from TestHFileBlock. Are you planning to address that? REVISION DETAIL https://reviews.facebook.net/D1521 > support checksums in HBase block cache > -------------------------------------- > > Key: HBASE-5074 > URL: https://issues.apache.org/jira/browse/HBASE-5074 > Project: HBase > Issue Type: Improvement > Components: regionserver > Reporter: dhruba borthakur > Assignee: dhruba borthakur > Attachments: D1521.1.patch, D1521.1.patch, D1521.2.patch, > D1521.2.patch, D1521.3.patch, D1521.3.patch, D1521.4.patch, D1521.4.patch, > D1521.5.patch, D1521.5.patch, D1521.6.patch, D1521.6.patch, D1521.7.patch, > D1521.7.patch, D1521.8.patch, D1521.8.patch, D1521.9.patch, D1521.9.patch > > > The current implementation of HDFS stores the data in one block file and the > metadata(checksum) in another block file. This means that every read into the > HBase block cache actually consumes two disk iops, one to the datafile and > one to the checksum file. This is a major problem for scaling HBase, because > HBase is usually bottlenecked on the number of random disk iops that the > storage-hardware offers. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira