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stack commented on HBASE-20716: ------------------------------- bq. beginner? consider me dubious about that classification, Stack. Dunno. Just replacing one usage w/ another? Will I change it [~mdrob]? > Unsafe access cleanup > --------------------- > > Key: HBASE-20716 > URL: https://issues.apache.org/jira/browse/HBASE-20716 > Project: HBase > Issue Type: Bug > Components: Performance > Reporter: stack > Priority: Minor > Labels: beginner > > 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)