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stack commented on HBASE-20716: ------------------------------- bq. Reduced the size of method by 40 bytes. Or, > 50%. That looks like massive savings on a bunch of methods that are on our hot paths. Thanks [~awked06] (Thanks in particular for the jmh'ing). > Unsafe access cleanup > --------------------- > > Key: HBASE-20716 > URL: https://issues.apache.org/jira/browse/HBASE-20716 > Project: HBase > Issue Type: Improvement > Components: Performance > Reporter: stack > Assignee: Sahil Aggarwal > Priority: Critical > Labels: beginner > Attachments: HBASE-20716.master.001.patch, Screen Shot 2018-06-26 at > 11.37.49 AM.png > > > We have two means of getting at unsafe; UnsafeAccess and then internal to the > Bytes class. They are effectively doing the same thing. We should have one > avenue to Unsafe only. > Many of our paths to Unsafe via UnsafeAccess traverse flags to check if > access is available, if it is aligned and the order in which words are > written on the machine. Each check costs -- especially if done millions of > times a second -- and on occasion adds bloat in hot code paths. The unsafe > access inside Bytes checks on startup what the machine is capable off and > then does a static assign of the appropriate class-to-use from there on out. > UnsafeAccess does not do this running the checks everytime. Would be good to > have the Bytes behavior pervasive. > The benefit of one access to Unsafe only is plain. The benefits we gain > removing checks will be harder to measure though should be plain when you > disassemble a hot-path; in a (very) rare case, the saved byte codes could be > the difference between inlining or not. -- This message was sent by Atlassian JIRA (v7.6.3#76005)