abstractdog commented on pull request #1280: URL: https://github.com/apache/hive/pull/1280#issuecomment-669038358
@zabetak : let me grab the opportunity to thank you for your [JMH benchmarks](https://issues.apache.org/jira/browse/HIVE-23880?focusedCommentId=17163111&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17163111)! it helped a lot, some of my findings from the last 2 weeks: 1. on cluster, JDK11 is better, in every scenario, we'll have to switch to that in LLAP daemons 2. more threads doesn't make any serious improvement <- that's the most important what I've found in the last two weeks...basically, my implementation was wrong, and the results got distorted by the improper usage of executor service (that's what is fixed in the new, squashed commit), so now, on the cluster I can see results which are in line with your JMH findings 3. removed automatic thread calculation: performance tests revealed that 1 thread is the most optimal, and can lead to serious improvements, this is something that cannot be measured from JMH easily because the advantage of 1 thread (which is the main task thread + 1 thread) is to decouple from the main thread, and let it handle other, probably CPU heavy stuff (waiting for inputs one by one, build vectorized row batches one by one, etc.), by this I reduced the task runtime by 50-60 seconds (170s -> 110s) 4. as agreed with @ashutoshc, I've left the support of multiple threads in the code, because we don't know if we can have the advantage of it later, and the split logic doesn't consume significant amount of resources...but I've set default 1 thread in HiveConf in order to let the user know that this is the recommended, optimal usage cc: @pgaref , @ashutoshc ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
