[jira] [Commented] (SPARK-24006) ExecutorAllocationManager.onExecutorAdded is an O(n) operation

["Hyukjin Kwon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-24006?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16442147#comment-16442147 ] 

Hyukjin Kwon commented on SPARK-24006:
--------------------------------------

How many executors would you guess cause an actual problem roughly?

> ExecutorAllocationManager.onExecutorAdded is an O(n) operation
> --------------------------------------------------------------
>
>                 Key: SPARK-24006
>                 URL: https://issues.apache.org/jira/browse/SPARK-24006
>             Project: Spark
>          Issue Type: Improvement
>          Components: Spark Core
>    Affects Versions: 2.3.0
>            Reporter: Xianjin YE
>            Priority: Major
>
> The ExecutorAllocationManager.onExecutorAdded is an O(n) operations, I believe it will be a problem when scaling out with large number of Executors as it effectively makes adding N executors at time complexity O(N^2).
>  
> I propose to invoke onExecutorIdle guarded by 
> {code:java}
> if (executorIds.size - executorsPendingToRemove.size >= minNumExecutors +1) { // Since we only need to re-remark idle executors when low bound
>     executorIds.filter(listener.isExecutorIdle).foreach(onExecutorIdle)
> } else {
>     onExecutorIdle(executorId)
> }{code}
> cc [~zsxwing]



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