wangyum opened a new pull request, #39671: URL: https://github.com/apache/spark/pull/39671
### What changes were proposed in this pull request? This PR update document recommends users to use JDK 8u362 and later versions. ### Why are the changes needed? 8u362 fixed a performance issue: https://github.com/openjdk/jdk8u-dev/pull/161 Benchmark code: ```scala val dir = "/tmp/spark/benchmark" val N = 2000000 val columns = Range(0, 100).map(i => s"id % $i AS id$i") spark.range(N).selectExpr(columns: _*).write.mode("Overwrite").parquet(dir) val cnt = 60 val selectExps = columns.take(cnt).map(_.split(" ").last).map(c => s"count(distinct $c)") val start = System.currentTimeMillis() spark.read.parquet(dir).selectExpr(selectExps: _*).collect() println(s"Benchmark result. Java version: ${System.getProperty("java.version")}. Time(ms): ${System.currentTimeMillis() - start}") ``` 8u352 benchmark result: ```shell export JAVA_HOME=/Users/yumwang/Downloads/zulu8.66.0.15-ca-jdk8.0.352-macosx_x64 export PATH=${JAVA_HOME}/bin:${PATH} bin/spark-shell --master "local[2]" -i benchmark.scala Benchmark result. Java version: 1.8.0_352. Time(ms): 641155 ``` 8u362 benchmark result: ```shell export JAVA_HOME=/Users/yumwang/Downloads/zulu8.68.0.19-ca-jdk8.0.362-macosx_x64 export PATH=${JAVA_HOME}/bin:${PATH} bin/spark-shell --master "local[2]" -i benchmark.scala Benchmark result. Java version: 1.8.0_362. Time(ms): 79360 ``` ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? N/A. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
