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.
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