kiszk commented on issue #23284: [SPARK-26337][SQL][TEST] Add benchmark for LongToUnsafeRowMap URL: https://github.com/apache/spark/pull/23284#issuecomment-446299651 To be honest, I cannot understand why the original performance degradation occurred. I think that read/write of `long` value does not require any sychronization or memory barrier without declaring `volatile`. At this [PR](https://github.com/apache/spark/pull/23204/files), `numKeyLookups` and `numProbes` are non-volatile long variables. I confirmed it by decompling a class file. However, I have no time to disassemble the generated code today and tomorrow. [Here](https://stackoverflow.com/questions/25173208/value-integrity-guarantee-for-concurrent-long-writes-in-64-bit-openjdk-7-8) is an article that addresses the similar topic regarding `static long`. cc @rednaxelafx
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