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https://issues.apache.org/jira/browse/STORM-1731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15259828#comment-15259828
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ASF GitHub Bot commented on STORM-1731:
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Github user satishd commented on the pull request:
https://github.com/apache/storm/pull/1362#issuecomment-215020195
+1. Nice to remove unnecessary lookups in critical paths.
[worker.clj#L768](https://github.com/apache/storm/blob/1.x-branch/storm-core/src/clj/org/apache/storm/daemon/worker.clj#L768)
HashMap instance is received in
[config.clj#L76](https://github.com/apache/storm/blob/1.x-branch/storm-core/src/clj/org/apache/storm/config.clj#L76)
from `Utils/readStormConfig` and converts that into clojure's
`PersistentHashMap` while `clojurify-structure` is done. This map is merged
later with other configs. This is all done when a worker is initialized.
Clojure's `PersistentHashMap` is based on _Hash Array Mapped Trie_ which can
have performance issues in critical paths for adding elements but lookups may
not cost much more than java's `HashMap` which uses an array with RB tree.
> Avoid looking up debug / backpressure enable flags within critical path
> -----------------------------------------------------------------------
>
> Key: STORM-1731
> URL: https://issues.apache.org/jira/browse/STORM-1731
> Project: Apache Storm
> Issue Type: Bug
> Components: storm-core
> Affects Versions: 1.0.0
> Reporter: Jungtaek Lim
> Assignee: Jungtaek Lim
> Priority: Critical
>
> While profiling the result of STORM-1729, I also found that there're many
> places in critical path which look up the value of flags which are not
> updated dynamically.
> ("get from map" is on top 5 from each spout / bolt thread.)
> This should be fixed.
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